United States securities and exchange commission logo October 18, 2022 Brendan Brennan Chief Financial Officer ICON PLC South County Business Park Leopardstown Dublin 18, D18 X5R3, Ireland Re: ICON PLC Form 20-F for Fiscal Year Ended December 31, 2021 Filed March 1, 2022 File No. 333-08704 Dear Brendan Brennan: 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 Trade & Services