United States securities and exchange commission logo September 8, 2021 Iain Mackay Chief Financial Officer GlaxoSmithKline plc 980 Great West Road Brentford, Middlesex TW8 9GS England Re: GlaxoSmithKline plc Form 20-F for the fiscal year ended December 31, 2020 Filed March 12, 2021 File No. 1-15170 Dear Mr. Mackay: We have completed our review of your filing. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Sincerely, Division of Corporation Finance Office of Life Sciences