PAGE 1
000 A000000 04/30/2015
000 C000000 0001562818
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 Y
000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 BLACKROCK MULTI SECTOR INCOME TRUST
001 B000000 811-22774
001 C000000 8002217210
002 A000000 100 BELLEVUE PARKWAY
002 B000000 WILMINGTON
002 C000000 DE
002 D010000 19809
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 N
007 B000000 0
007 C010100 1
008 A000001 BLACKROCK ADVISORS, LLC
008 B000001 A
008 C000001 801-47710
008 D010001 WILMINGTON
008 D020001 DE
008 D030001 19809
008 A000002 BLACKROCK SINGAPORE LIMITED
008 B000002 S
008 C000002 801-76926
008 D010002 SINGAPORE
008 D050002 SINGAPORE
012 A000001 COMPUTERSHARE TRUST COMPANY, N.A.
012 B000001 85-11340
012 C010001 CANTON
012 C020001 MA
012 C030001 02021
013 A000001 DELOITTE & TOUCHE LLP
013 B010001 BOSTON
013 B020001 MA
013 B030001 02116
014 A000001 BLACKROCK EXECUTION SERVICES
014 B000001 8-48719
014 A000002 BLACKROCK INVESTMENTS, LLC
014 B000002 8-48436
014 A000003 HARRIS WILLIAMS LLC
014 B000003 8-53380
014 A000004 PNC CAPITAL MARKETS, INC.
014 B000004 8-32493
PAGE 2
014 A000005 PNC INVESTMENTS LLC
014 B000005 8-66195
015 A000001 STATE STREET BANK & TRUST COMPANY
015 B000001 C
015 C010001 BOSTON
015 C020001 MA
015 C030001 02110
015 E010001 X
015 A000002 BANK OF NEW YORK MELLON
015 B000002 S
015 C010002 NEW YORK
015 C020002 NY
015 C030002 10286
015 E010002 X
015 A000003 CITIBANK N.A.
015 B000003 S
015 C010003 BUENOS AIRES
015 D010003 ARGENTINA
015 E040003 X
015 A000004 HSBC AUSTRALIA
015 B000004 S
015 C010004 SYDNEY
015 D010004 AUSTRALIA
015 D020004 NSW2000
015 E040004 X
015 A000005 STATE STREET TRUST COMPANY CANADA
015 B000005 S
015 C010005 TORONTO
015 D010005 CANADA
015 D020005 M5V 3L3
015 E040005 X
015 A000006 CLEARSTREAM BANKING SA
015 B000006 S
015 C010006 LUXEMBOURG
015 D010006 LUXEMBOURG
015 E040006 X
015 A000007 DEUTSCHE BANK
015 B000007 S
015 C010007 MILAN
015 D010007 ITALY
015 D020007 20124
015 E040007 X
015 A000008 BANCO NACIONAL DE MEXICO SA
015 B000008 S
015 C010008 MEXICO CITY
015 D010008 MEXICO
015 D020008 01210
015 E040008 X
015 A000009 HSBC NEW ZEALAND
015 B000009 S
015 C010009 AUCKLAND
PAGE 3
015 D010009 NEW ZEALAND
015 E040009 X
015 A000010 SEB NORWAY
015 B000010 S
015 C010010 OSLO
015 D010010 NORWAY
015 D020010 NO-0123
015 E040010 X
015 A000011 STATE STREET BANK
015 B000011 S
015 C010011 LONDON
015 D010011 UNITED KINGDOM
015 E040011 X
015 A000012 FIRSTRAND BANK LIMITED
015 B000012 S
015 C010012 JOHANNESBURG
015 D010012 SOUTH AFRICA
015 D020012 2001
015 E020012 X
015 A000013 UNICREDIT BANK HUNGARY ZRT
015 B000013 S
015 C010013 BUDAPEST
015 D010013 HUNGARY
015 D020013 H-1054
015 E040013 X
015 A000014 THE HONGKONG + SHANGHAI BANKING COR
015 B000014 S
015 C010014 Shanghai
015 D010014 China
015 E040014 X
015 A000015 BANK HANDLOWY W WARSZAWIE SA
015 B000015 S
015 C010015 WARSAW
015 D010015 POLAND
015 D020015 00-249
015 E040015 X
018 000000 Y
019 A000000 Y
019 B000000 285
019 C000000 BLKRKADVSR
021 000000 0
022 A000001 DEUTSCHE BANK SECURITIES INC
022 B000001 13-2730828
022 C000001 301760
022 D000001 188493
022 A000002 BARCLAYS CAPITAL INC.
022 B000002 06-1031656
022 C000002 113712
022 D000002 285330
022 A000003 STATE STREET BANK AND TRUST COMPANY
022 B000003 04-1867445
PAGE 4
022 C000003 173664
022 D000003 164099
022 A000004 BNP PARIBAS
022 B000004 13-3235334
022 C000004 18927
022 D000004 202148
022 A000005 UBS SECURITIES LLC
022 B000005 13-3873456
022 C000005 35455
022 D000005 128268
022 A000006 J.P. MORGAN SECURITIES INC
022 B000006 13-3379014
022 C000006 11894
022 D000006 70835
022 A000007 CITIGROUP GLOBAL MARKETS INC
022 B000007 11-2418191
022 C000007 22849
022 D000007 12306
022 A000008 WELLS FARGO & CO
022 B000008 41-0449260
022 C000008 10516
022 D000008 18058
022 A000009 CREDIT SUISSE SECURITIES USA L.L.C.
022 B000009 13-5659485
022 C000009 3915
022 D000009 21130
022 A000010 RBC CAPITAL MARKETS CORP
022 B000010 13-5033225
022 C000010 3783
022 D000010 21250
023 C000000 723852
023 D000000 1167690
024 000000 Y
025 A000001 CREDIT SUISSE
025 B000001 13-3442768
025 C000001 D
025 D000001 6070
025 A000002 J.P. MORGAN SECURITIES INC
025 B000002 13-3379014
025 C000002 D
025 D000002 15475
025 A000003 WELLS FARGO & CO
025 B000003 41-0449260
025 C000003 D
025 D000003 9218
025 A000004 CITIGROUP GLOBAL MARKETS INC.
025 B000004 11-2418191
025 C000004 D
025 D000004 18157
025 A000005 BNP PARIBAS
025 B000005 13-3235334
PAGE 5
025 C000005 D
025 D000005 9019
025 A000006 CITIGROUP GLOBAL MARKETS HOLDINGS INC
025 B000006 11-2418067
025 C000006 E
025 D000006 2042
026 A000000 N
026 B000000 N
026 C000000 N
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 N
028 A010000 0
028 A020000 0
028 A030000 0
028 A040000 0
028 B010000 0
028 B020000 0
028 B030000 0
028 B040000 0
028 C010000 0
028 C020000 0
028 C030000 0
028 C040000 0
028 D010000 0
028 D020000 0
028 D030000 0
028 D040000 0
028 E010000 0
028 E020000 0
028 E030000 0
028 E040000 0
028 F010000 0
028 F020000 0
028 F030000 0
028 F040000 0
028 G010000 0
028 G020000 0
028 G030000 0
028 G040000 0
028 H000000 0
030 A000000 0
030 B000000 0.00
030 C000000 0.00
031 A000000 0
031 B000000 0
032 000000 0
PAGE 6
033 000000 0
035 000000 0
036 B000000 0
038 000000 0
042 A000000 0
042 B000000 0
042 C000000 0
042 D000000 0
042 E000000 0
042 F000000 0
042 G000000 0
042 H000000 0
043 000000 0
044 000000 0
045 000000 Y
046 000000 N
047 000000 Y
048 000000 0.800
048 A010000 0
048 A020000 0.000
048 B010000 0
048 B020000 0.000
048 C010000 0
048 C020000 0.000
048 D010000 0
048 D020000 0.000
048 E010000 0
048 E020000 0.000
048 F010000 0
048 F020000 0.000
048 G010000 0
048 G020000 0.000
048 H010000 0
048 H020000 0.000
048 I010000 0
048 I020000 0.000
048 J010000 0
048 J020000 0.000
048 K010000 0
048 K020000 0.000
049 000000 N
050 000000 N
051 000000 N
052 000000 N
053 A000000 Y
053 B000000 Y
053 C000000 N
054 A000000 Y
054 B000000 Y
054 C000000 N
054 D000000 N
PAGE 7
054 E000000 N
054 F000000 N
054 G000000 N
054 H000000 Y
054 I000000 N
054 J000000 Y
054 K000000 N
054 L000000 N
054 M000000 Y
054 N000000 N
054 O000000 N
055 A000000 Y
055 B000000 Y
056 000000 Y
057 000000 N
058 A000000 N
059 000000 Y
060 A000000 N
060 B000000 N
061 000000 0
062 A000000 Y
062 B000000 0.0
062 C000000 50.3
062 D000000 0.0
062 E000000 0.0
062 F000000 0.0
062 G000000 0.0
062 H000000 0.0
062 I000000 0.0
062 J000000 0.0
062 K000000 0.0
062 L000000 3.8
062 M000000 0.0
062 N000000 0.0
062 O000000 0.0
062 P000000 56.6
062 Q000000 61.0
062 R000000 4.3
063 A000000 0
063 B000000 20.6
064 A000000 N
064 B000000 N
066 A000000 N
067 000000 N
068 A000000 N
068 B000000 N
069 000000 N
070 A010000 Y
070 A020000 N
070 B010000 Y
070 B020000 N
PAGE 8
070 C010000 Y
070 C020000 N
070 D010000 Y
070 D020000 N
070 E010000 Y
070 E020000 Y
070 F010000 Y
070 F020000 N
070 G010000 Y
070 G020000 N
070 H010000 Y
070 H020000 N
070 I010000 N
070 I020000 N
070 J010000 Y
070 J020000 N
070 K010000 Y
070 K020000 Y
070 L010000 Y
070 L020000 Y
070 M010000 Y
070 M020000 Y
070 N010000 Y
070 N020000 N
070 O010000 Y
070 O020000 Y
070 P010000 Y
070 P020000 N
070 Q010000 N
070 Q020000 N
070 R010000 Y
070 R020000 Y
071 A000000 87222
071 B000000 181844
071 C000000 1338018
071 D000000 7
072 A000000 6
072 B000000 36221
072 C000000 1903
072 D000000 0
072 E000000 0
072 F000000 5421
072 G000000 51
072 H000000 0
072 I000000 25
072 J000000 66
072 K000000 0
072 L000000 10
072 M000000 34
072 N000000 7
072 O000000 0
PAGE 9
072 P000000 2081
072 Q000000 0
072 R000000 55
072 S000000 46
072 T000000 0
072 U000000 0
072 V000000 0
072 W000000 41
072 X000000 7837
072 Y000000 7
072 Z000000 30294
072AA000000 0
072BB000000 4468
072CC010000 0
072CC020000 1910
072DD010000 27206
072DD020000 0
072EE000000 0
073 A010000 0.7842
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 2864
074 B000000 0
074 C000000 0
074 D000000 1127730
074 E000000 176505
074 F000000 0
074 G000000 0
074 H000000 5
074 I000000 29942
074 J000000 0
074 K000000 3075
074 L000000 13615
074 M000000 101
074 N000000 1353837
074 O000000 5958
074 P000000 880
074 Q000000 0
074 R010000 586130
074 R020000 0
074 R030000 8
074 R040000 3714
074 S000000 0
074 T000000 757147
074 U010000 38422
074 U020000 0
074 V010000 19.71
074 V020000 0.00
074 W000000 0.0000
074 X000000 8093
PAGE 10
074 Y000000 230385
075 A000000 0
075 B000000 753726
076 000000 17.59
077 A000000 Y
077 B000000 N
077 C000000 N
077 D000000 N
077 E000000 N
077 F000000 N
077 G000000 N
077 H000000 N
077 I000000 N
077 J000000 N
077 K000000 N
077 L000000 N
077 M000000 N
077 N000000 N
077 O000000 Y
077 P000000 N
077 Q010000 N
077 Q020000 N
077 Q030000 N
078 000000 N
080 C000000 0
081 B000000 0
082 B000000 0
083 B000000 0
084 B000000 0
086 A010000 0
086 A020000 0
086 B010000 0
086 B020000 0
086 C010000 0
086 C020000 0
086 D010000 0
086 D020000 0
086 E010000 0
086 E020000 0
086 F010000 0
086 F020000 0
087 A010000 COMMON STOCK
087 A020000 09258A107
087 A030000 BIT
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 N
SIGNATURE NEAL J. ANDREWS
TITLE CFO