Transaction in Own Shares

GlaxoSmithKline PLC
21 September 2006


GlaxoSmithKline plc (the "Company") announces that in accordance with the
authority granted by shareholders at the Company's Annual General Meeting on 17
May 2006 it purchased 700,000 of its Ordinary shares of 25 pence each ("shares")
on 21 September, 2006 at a price of 1428.0127 pence per share.

The Company intends to hold these shares in Treasury.

Following the purchase of these shares, the Company holds 195,891,678 of its
shares in Treasury and has 5,790,313,164 shares in issue (excluding Treasury
shares).

This announcement does not constitute, or form part of, an offer or any
solicitation of an offer to purchase or subscribe for securities in any
jurisdiction.


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