Director/PDMR Shareholding

GlaxoSmithKline PLC
21 February 2008



   Notification of Transactions of Directors, Persons Discharging Managerial
                                 Responsibility


I give below details of changes in the interests of:


•    Directors and Persons Discharging Managerial Responsibility in the Ordinary
Shares of GlaxoSmithKline plc in respect of the under mentioned persons arising
from the sale of Ordinary Shares at a price of £11.40 per Ordinary Share on 20
February 2008 to meet their tax liabilities following the vesting of a
Performance Share Plan (PSP) award:


                     No. of Ordinary Shares sold to meet tax liabilities 
                     following the vesting of a PSP award
Mr A P Witty*                                        13,642
Mr R M Bondy                                         13,642
Mr M Dunoyer                                          5,138
Dr M Slaoui*                                          3,640
Mr J S Heslop*                                        2,746
Mr E J Gray                                           3,763
Mr J M Clarke                                         8,482
Mr D Learmouth                                        1,776

            * Denotes an Executive Director


•    Persons Discharging Managerial Responsibility in the American Depositary
Shares (ADSs) of GlaxoSmithKline plc in respect of the under mentioned persons
arising from the withholding of shares at a price of $44.75 per ADS on 20
February 2008 to meet their tax liabilities following the vesting of a
Performance Share Plan award:


                     No. of ADSs withheld to meet tax liabilities following 
                     the vesting of a PSP award
Dr JP Garnier*                                       34,117
Mr D M Stout                                         10,859
Mr D J Phelan                                         5,613
Mr C Viehbacher*                                      5,397
Mr D Pulman                                           4,425
Mr W C Louv                                           1,445

            * Denotes an Executive Director



The Company, Directors, Persons Discharging Managerial Responsibility were
advised of these transactions on 21 February 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

21 February 2008



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