SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  SCHEDULE 13D

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                           (AMENDMENT NO___________)*


                               BIOTRANSPLANT INC.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                   09066Y 10 7
--------------------------------------------------------------------------------
                                 (CUSIP Number)

                             W. Stephen Holmes, III
                               3000 Sand Hill Road
                              Building 3, Suite 255
                              Menlo Park, CA 94025
--------------------------------------------------------------------------------
           (Name, Address and Telephone Number of Person Authorized to
                       Receive Notices and Communications)


                                  May 16, 2001
--------------------------------------------------------------------------------
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously  filed a statement on Schedule 13G to report
the  acquisition  which is the subject of this  Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box
[ ]

Note:  Schedules  filed in paper format shall include a signed original and five
copies of the  schedule,  including  all  exhibits.  See Rule 13d-7(b) for other
parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934, as amended (the "Exchange Act") or otherwise subject to the liabilities of
that section of the Exchange Act but shall be subject to all other provisions of
the Exchange Act (however, see the Notes).

                                       1.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest Partners V, LP

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  |_|
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
----------- ------------------------------------------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   619,091
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              619,091
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            619,091
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.5%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by InterWest  Partners VI, LP that it
is the  beneficial  owner of any of the  Common  Stock  referred  to herein  for
purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or
for any other purpose, and such beneficial ownership is expressly disclaimed.

                                       2.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest Partners VI, LP

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   577,679
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              577,679
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            577,679
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:     [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.3%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by InterWest  Partners VI, LP that it
is the  beneficial  owner of any of the  Common  Stock  referred  to herein  for
purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or
for any other purpose, and such beneficial ownership is expressly disclaimed.

                                       3.






         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest Investors V

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   3,891
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              3,891
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            3,891
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            Less than 1%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute  an admission by InterWest  Investors V that it is
the beneficial  owner of any of the Common Stock referred to herein for purposes
of Section 13(d) of the Securities  Exchange Act of 1934, as amended, or for any
other purpose, and such beneficial ownership is expressly disclaimed.

                                       4.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest Investors VI, LP

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   18,111
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              18,111
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            18,111
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            Less than 1%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by InterWest Investors VI, LP that it
is the  beneficial  owner of any of the  Common  Stock  referred  to herein  for
purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or
for any other purpose, and such beneficial ownership is expressly disclaimed.


                                       5.




         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest   Management  Partners  V,  LP  (the  general  partner  of InterWest Partners V, LP)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   619,091
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              619,091
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            619,091
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.5%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by InterWest  Management  Partners V,
LP (the general  partner of InterWest  Partners V, LP) that it is the beneficial
owner of any of the Common  Stock  referred  to herein for  purposes  of Section
13(d) of the  Securities  Exchange  Act of 1934,  as  amended,  or for any other
purpose, and such beneficial ownership is expressly disclaimed.

                                       6.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            InterWest Management Partners VI, LLC (the general partner of InterWest Partners VI, LP and InterWest Investors VI, LP)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            California
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   595,790
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              595,790
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            0
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            595,790
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.4%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            PN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by InterWest  Management Partners VI,
LLC (the general  partner of InterWest  Partners VI, LP and InterWest  Investors
VI, LP) that it is the  beneficial  owner of any of the Common Stock referred to
herein for purposes of Section 13(d) of the Securities  Exchange Act of 1934, as
amended,  or for any other purpose,  and such beneficial  ownership is expressly
disclaimed.

                                       7.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Harvey B. Cash (a Special Limited Partner of InterWest  Management  Partners V, LP and a Managing  Director of InterWest
            Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 595,790
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            595,790
--------------------------------- ---------- ---------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            595,790
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.4%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by Harvey B. Cash (a Special  Limited
Partner  of  InterWest  Management  Partners  V, LP and a Managing  Director  of
InterWest Management Partners VI, LLC) that it is the beneficial owner of any of
the Common  Stock  referred  to herein  for  purposes  of  Section  13(d) of the
Securities Exchange Act of 1934, as amended, or for any other purpose,  and such
beneficial ownership is expressly disclaimed.

                                       8.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Alan W. Crites (a General Partner of InterWest Management Partners V, LP, a General Partner of InterWest Investors V and
            a Managing Director of InterWest Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,218,772
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by Alan W. Crites (a General  Partner
of InterWest Management Partners V, LP, a General Partner of InterWest Investors
V and a Managing Director of InterWest  Management  Partners VI, LLC) that it is
the beneficial  owner of any of the Common Stock referred to herein for purposes
of Section 13(d) of the Securities  Exchange Act of 1934, as amended, or for any
other purpose, and such beneficial ownership is expressly disclaimed.

                                       9.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Philip T.  Gianos (a General  Partner of  InterWest  Management  Partners  V, LP and a Managing  Director  of  InterWest
            Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,214,881
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,214,881
--------------------------------- ---------- ---------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,214,881
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by  Philip T.  Gianos (a  General
Partner  of  InterWest  Management  Partners  V, LP and a Managing  Director  of
InterWest Management Partners VI, LLC) that it is the beneficial owner of any of
the Common  Stock  referred  to herein  for  purposes  of  Section  13(d) of the
Securities Exchange Act of 1934, as amended, or for any other purpose,  and such
beneficial ownership is expressly disclaimed.

                                       10.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            W. Scott Hedrick (a General Partner of InterWest Management Partners V, LP, a General Partner of InterWest Investors V
            and a Managing Director of InterWest Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,218,772
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:   [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by W.  Scott  Hedrick  (a General
Partner of InterWest  Management  Partners V, LP, a General Partner of InterWest
Investors V and a Managing  Director of InterWest  Management  Partners VI, LLC)
that it is the  beneficial  owner of any of the Common Stock  referred to herein
for  purposes  of  Section  13(d) of the  Securities  Exchange  Act of 1934,  as
amended,  or for any other purpose,  and such beneficial  ownership is expressly
disclaimed.

                                      11.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            W. Stephen Holmes (a General Partner of InterWest Management Partners V, LP, a General Partner of InterWest Investors V
            and a Managing Director of InterWest Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,218,772
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,218,772
--------------------------------- ---------- ---------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by W.  Stephen  Holmes (a General
Partner of InterWest  Management  Partners V, LP, a General Partner of InterWest
Investors V and a Managing  Director of InterWest  Management  Partners VI, LLC)
that it is the  beneficial  owner of any of the Common Stock  referred to herein
for  purposes  of  Section  13(d) of the  Securities  Exchange  Act of 1934,  as
amended,  or for any other purpose,  and such beneficial  ownership is expressly
disclaimed.

                                      12.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Gilbert H. Kliman (a Venture Member of InterWest Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 595,790
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            595,790
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            595,790
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.4%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by Gilbert  H.  Kliman (a Venture
Member of InterWest Management Partners VI, LLC) that it is the beneficial owner
of any of the Common Stock  referred to herein for purposes of Section  13(d) of
the Securities Exchange Act of 1934, as amended,  or for any other purpose,  and
such beneficial ownership is expressly disclaimed.

                                      13.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Robert R. Momsen (a General Partner of InterWest  Management  Partners V, LP, a General Partner of InterWest Investors V
            and a Managing Director of InterWest Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,218,772
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,218,772
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by  Robert R.  Momsen (a  General
Partner of InterWest  Management  Partners V, LP, a General Partner of InterWest
Investors V and a Managing  Director of InterWest  Management  Partners VI, LLC)
that it is the  beneficial  owner of any of the Common Stock  referred to herein
for  purposes  of  Section  13(d) of the  Securities  Exchange  Act of 1934,  as
amended,  or for any other purpose,  and such beneficial  ownership is expressly
disclaimed.

                                       14.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Arnold L.  Oronsky (a General  Partner of  InterWest  Management  Partners V, LP and a Managing  Director  of  InterWest
            Management Partners VI, LLC)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 1,214,881
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            1,214,881
--------------------------------- ---------- ---------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,214,881
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.9%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to  constitute  an  admission  by Arnold L.  Oronsky  (a General
Partner  of  InterWest  Management  Partners  V, LP and a Managing  Director  of
InterWest Management Partners VI, LLC) that it is the beneficial owner of any of
the Common  Stock  referred  to herein  for  purposes  of  Section  13(d) of the
Securities Exchange Act of 1934, as amended, or for any other purpose,  and such
beneficial ownership is expressly disclaimed.

                                       15.





         
=========== ========================================================================================================================
    1       NAME OF REPORTING PERSONS

            Wallace Hawley (a General Partner of InterWest Partners V, LP and InterWest Investors V)

            S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS


----------- ------------------------------------------------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                     (a)      [ ]
                     (b)      [X]
----------- ------------------------------------------------------------------------------------------------------------------------
    3       SEC USE ONLY

----------- ------------------------------------------------------------------------------------------------------------------------
    4       SOURCE OF FUNDS

            OO
----------- ------------------------------------------------------------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------- ---------- ---------------------------------------------------------------------------------------
           NUMBER OF                  7      SOLE VOTING POWER                   0
             SHARES
          BENEFICIALLY
            OWNED BY
           REPORTING
             PERSON
              WITH
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      8      SHARED VOTING POWER                 622,982
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                      9      SOLE DISPOSITIVE POWER              0
--------------------------------- ---------- ---------------------------------------------------------------------------------------
                                     10      SHARED DISPOSITIVE POWER            622,982
----------- ------------------------------------------------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            622,982
----------- ------------------------------------------------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:    [ ]
----------- ------------------------------------------------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            3.5%
----------- ------------------------------------------------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON

            IN
=========== ========================================================================================================================

Neither the filing of this  statement  on Schedule  13D nor any of its  contents
shall be deemed to constitute an admission by Wallace Hawley (a General  Partner
of InterWest Partners V, LP and InterWest Investors V) that it is the beneficial
owner of any of the Common  Stock  referred  to herein for  purposes  of Section
13(d) of the  Securities  Exchange  Act of 1934,  as  amended,  or for any other
purpose, and such beneficial ownership is expressly disclaimed.

                                      16.



ITEM 1.  SECURITY AND ISSUER

This statement on Schedule 13D relates to the Common Stock (the "Common  Stock")
of BioTransplant Inc., a Delaware corporation  ("BioTransplant").  The principal
executive  offices of  BioTransplant  are located at Building 75, Third  Avenue,
Building 96 13th Street, Charleston, MA 02129.

ITEM 2.  IDENTITY AND BACKGROUND

             (a)-(b) The undersigned  hereby file this Schedule 13D Statement on
                  behalf of InterWest Partners V, LP ("IW5"), InterWest Partners
                  VI, LP  ("IW6"),  InterWest  Investors  V  ("II5"),  InterWest
                  Investors VI, LP ("II6"),  InterWest Management Partners V, LP
                  ("IMP5"),  InterWest  Management  Partners VI, LLC,  ("IMP6"),
                  Harvey B. Cash  ("HBC"),  Alan W.  Crites  ("AWC"),  Philip T.
                  Gianos ("PTG"),  W. Scott Hedrick  ("WSH"),  W. Stephen Holmes
                  III  ("SH"),  Robert R.  Momsen  ("RRM"),  Arnold  L.  Oronsky
                  ("ALO") Gilbert H. Kliman ("GHK"), and Wallace Hawley ("WRH").
                  IW5, IW6, II5 and II6 are venture  capital funds.  IMP5 is the
                  general partner of IW5. IMP6 is the general partner of IW6 and
                  II6. HBC is a special  limited  partner of IMP5 and a managing
                  director of IMP6.  AWC,  PTG, WSH, SH, RRM and ALO are general
                  partners  of IMP5 and  managing  directors  of IMP6.  GHK is a
                  venture  partner of IMP6. WRH is a general  partner of IW5 and
                  II5.  AWC,  WSH, SH and RRM are also general  partners of II5.
                  The address of the  principal  office for each of the above is
                  3000 Sand Hill Road,  Building 3, Suite 255,  Menlo  Park,  CA
                  94025.

             (c)  Each of HBC,  AWC,  PTG,  WSH, SH, GHK,  RRM, ALO and WRH is a
                  venture capitalist.

             (d)-(e) Not applicable.

             (f)  All of the  individuals  named in Schedule I to this  Schedule
                  13D are citizens of the United States.

ITEM 3.  SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

Under the terms of the Agreement and Plan of Merger  entered into by and between
BioTransplant  and Eligix,  Inc.  ("Eligix"),  BioTransplant  plans to issue 6.6
million shares of its Common Stock to the Eligix holders in exchange for all the
outstanding  Eligix shares.  The persons filing this statement  exchanged  their
shares of Eligix for the shares of BioTransplant described in this statement.

ITEM 4.  PURPOSE OF TRANSACTION

As noted in Item 3 above,  the Common Stock was issued in exchange for shares of
Eligix held by the persons filing this statement.

ITEM 5.  INTEREST IN SECURITIES OF THE ISSUER



                                                                                             
=================================== ===================== ======================= ====================== =====================
                                            IW5                    IW6                     II5                   II6
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Beneficial Ownership                       619,091                577,679                  3,891                18,111
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Percentage of Class                           3.5%                   3.3%                      *                     *
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Voting Power                          619,091                577,679                  3,891                18,111
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Voting Power                              0                      0                      0                     0
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Dispositive Power                     619,091                577,679                  3,891                18,111
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Dispositive Power                         0                      0                      0                     0
=================================== ===================== ======================= ====================== =====================


=================================== ===================== ======================= ====================== =====================
                                            IMP5                   IMP6                    HBC                   AWC
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Beneficial Ownership                       619,091                595,790                595,790             1,218,772
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Percentage of Class                           3.5%                   3.4%                   3.4%                  6.9%
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Voting Power                          619,091                595,790                      0                     0
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Voting Power                              0                      0                595,790             1,218,772
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Dispositive Power                     619,091                595,790                      0                     0
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Dispositive Power                         0                      0                595,790             1,218,772
=================================== ===================== ======================= ====================== =====================



* less than 1%

                                      17.



=================================== ===================== ======================= ====================== =====================
                                            PTG                    WSH                     SH                    GHK
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Beneficial Ownership                     1,214,881              1,218,772              1,218,772               595,790
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Percentage of Class                           6.9%                   6.9%                   6.9%                  3.4%
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Voting Power                                0                      0                      0                     0
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Voting Power                      1,214,881              1,218,772              1,218,772               595,790
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Sole Dispositive Power                           0                      0                      0                     0
----------------------------------- --------------------- ----------------------- ---------------------- ---------------------
Shared Dispositive Power                 1,214,881              1,218,772              1,218,772               595,790
=================================== ===================== ======================= ====================== =====================


=================================== ====================== ===================== =====================
                                             RRM                   ALO                   WRH
----------------------------------- ---------------------- --------------------- ---------------------
Beneficial Ownership                     1,218,772             1,214,881               622,982
----------------------------------- ---------------------- --------------------- ---------------------
Percentage of Class                           6.9%                  6.9%                  3.5%
----------------------------------- ---------------------- --------------------- ---------------------
Sole Voting Power                                0                     0                     0
----------------------------------- ---------------------- --------------------- ---------------------
Shared Voting Power                      1,218,772             1,214,881               622,982
----------------------------------- ---------------------- --------------------- ---------------------
Sole Dispositive Power                           0                     0                     0
----------------------------------- ---------------------- --------------------- ---------------------
Shared Dispositive Power                 1,218,772             1,214,881               622,982
=================================== ====================== ===================== =====================


ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO
SECURITIES OF THE ISSUER

Other than as described  in Item 4 or Item 5 above,  to  InterWest's  knowledge,
there are no contracts, arrangements,  understandings or relationships (legal or
otherwise)  among the persons  named in Item 2 and between  such persons and any
person  with  respect to any  securities  of  BioTransplant,  including  but not
limited to transfer or voting of any of the  securities,  finder's  fees,  joint
ventures,  loan or option  arrangements,  puts or calls,  guarantees of profits,
division of profits or loss, or the giving or withholding of proxies.

ITEM 7.  MATERIAL TO BE FILED AS EXHIBITS

Joint Filing Statement attached as Exhibit A.


                                      18.




                                    SIGNATURE

After  reasonable  inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Date:  May 24, 2001



                                             
INTERWEST PARTNERS V, LP                        INTERWEST PARTNERS VI, LP

By: InterWest Management Partners V, LP         By:  InterWest Management Partners VI, LLC
    its General Partner                              its General Partner

By:                                             By:
    --------------------------------                 --------------------------------
    General Partner                                  Managing Director

INTERWEST INVESTORS V                           INTERWEST INVESTORS VI, LP

                                                By:  InterWest Management Partners VI, LLC
                                                     its General Partner
By:
    --------------------------------
    General Partner                             By:
                                                     --------------------------------
                                                     Managing Director

INTERWEST MANAGEMENT PARTNERS V, LP             INTERWEST MANAGEMENT PARTNERS VI, LLC

By:                                             By:
    --------------------------------                 --------------------------------
             General Partner                         Managing Director

HARVEY B. CASH                                  W. STEPHEN HOLMES

-------------------------                       -------------------------
ALAN W. CRITES                                  GILBERT H. KLIMAN

-------------------------                       -------------------------
PHILIP T. GIANOS                                ROBERT R. MOMSEN

-------------------------                       -------------------------
W. SCOTT HEDRICK                                ARNOLD L. ORONSKY

-------------------------                       -------------------------
WALLACE HAWLEY

-------------------------


                                      19.




EXHIBIT A


                             Joint Filing Statement


         We, the  undersigned,  hereby  express our agreement  that the attached
Schedule 13D is filed on behalf of each of us.


                                             
INTERWEST PARTNERS V, LP                             INTERWEST PARTNERS VI, LP

By: InterWest Management Partners V, LP         By:  InterWest Management Partners VI, LLC
    its General Partner                              its General Partner

By:                                             By:
    --------------------------------                 --------------------------------
    General Partner                                  Managing Director

INTERWEST INVESTORS V                           INTERWEST INVESTORS VI, LP

                                                By:  InterWest Management Partners VI, LLC
                                                     its General Partner
By:
    --------------------------------
    General Partner                             By:
                                                     --------------------------------
                                                     Managing Director

INTERWEST MANAGEMENT PARTNERS V, LP             INTERWEST MANAGEMENT PARTNERS VI, LLC

By:                                             By:
    --------------------------------                 --------------------------------
    General Partner                                  Managing Director

HARVEY B. CASH                                  W. STEPHEN HOLMES

-------------------------                       -------------------------
ALAN W. CRITES                                  GILBERT H. KLIMAN

-------------------------                       -------------------------
PHILIP T. GIANOS                                ROBERT R. MOMSEN

-------------------------                       -------------------------
W. SCOTT HEDRICK                                ARNOLD L. ORONSKY

-------------------------                       -------------------------
WALLACE HAWLEY

-------------------------



                                      20.