United States securities and exchange commission logo May 14, 2020 Michael Bristow, M.D. President ARCA biopharma, Inc. 11080 Circle Point Road, Suite 140 Westminster, CO 80020 Re: ARCA biopharma, Inc. Registration Statement on Form S-3 Filed May 7, 2020 File No. 333-238067 Dear Dr. Bristow: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding requests for acceleration. 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. Please contact Paul Fischer at 202-551-3415 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Brent Fassett, Esq.