United States securities and exchange commission logo May 19, 2021 Gerrit Dispersyn, Dr. Med. Sc President and Chief Executive Officer Phio Pharmaceuticals Corp. 257 Simarano Drive, Suite 101 Marlborough, MA 01752 Re: Phio Pharmaceuticals Corp. Registration Statement on Form S-3 Filed May 13, 2021 File No. 333-256100 Dear Dr. Dispersyn: 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 Jeffrey Gabor at 202-551-2544 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Ryan A. Murr, Esq.