FORM 6-K



                       SECURITIES AND EXCHANGE COMMISSION
                              Washington D.C. 20549



                            Report of Foreign Issuer



                      Pursuant to Rule 13a-16 or 15d-16 of
                       the Securities Exchange Act of 1934


                         For period ending April 14, 2008

                               GlaxoSmithKline plc
                              (Name of registrant)



               980 Great West Road, Brentford, Middlesex, TW8 9GS
                    (Address of principal executive offices)


             Indicate by check mark whether the registrant files or
                 will file annual reports under cover Form 20-F
                                  or Form 40-F


                              Form 20-F x Form 40-F
                                       --


         Indicate by check mark whether the registrant by furnishing the
        information contained in this Form is also thereby furnishing the
       information to the Commission pursuant to Rule 12g3-2(b) under the
                        Securities Exchange Act of 1934.

                                    Yes No x
                                       --






   Notification of Transactions of Directors, Persons Discharging Managerial
                      Responsibility or Connected Persons


I give below details of an increase in interests in the Ordinary shares of
GlaxoSmithKline plc in respect of the personal holdings of the under-mentioned
persons at a price of GBP11.07 per Ordinary share, following the re-investment
of the dividend paid to shareholders on 10 April 2008.



Mr J S Heslop                            459
Mrs P A Heslop                           110
Mr D Learmouth                           106
Dr D Pulman                              207
Mrs C R Pulman                            69
Mr A P Witty                              34
Mrs C M Witty                            456



The Company and the above named persons were advised of this information on 14
April 2008.


This notification relates to a transaction notified in accordance with
Disclosure and Transparency Rule 3.1.4R(1)(a).





S M Bicknell
Company Secretary



14 April 2008



SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorised.



                                                             GlaxoSmithKline plc
                                                                    (Registrant)

Date: April 14, 2008                                          By: VICTORIA WHYTE
                                                              ------------------
                                                              Victoria Whyte
                                                 Authorised Signatory for and on
                                                   behalf of GlaxoSmithKline plc