United States securities and exchange commission logo

                          August 11, 2020

       William Huyett
       Chief Financial Officer
       Cyclerion Therapeutics, Inc.
       301 Binney Street
       Cambridge, Massachusetts, 02142

                                                        Re: Cyclerion
Therapeutics, Inc.
Statement on Form S-3
                                                            Filed August 7,
                                                            File No. 333-242334

       Dear Mr. Huyett:

              This is to advise you that we have not reviewed and will not
review your registration

               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 Margaret
Schwartz at 202-551-7153 with any questions.


                          Division of Corporation Finance

                          Office of Life Sciences