United States securities and exchange commission logo

                           August 12, 2020

       William Duke, Jr.
       Chief Financial Officer
       Kaleido Biosciences, Inc.
       65 Hayden Avenue
       Lexington, MA 02421

                                                        Re: Kaleido
Biosciences, Inc.
Statement on Form S-3
                                                            Filed August 4,
                                                            File No. 333-240323

       Dear Mr. Duke:

              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 Chris
Edwards at (202) 551-6761 with any questions.


                           Division of Corporation Finance

                           Office of Life Sciences
       cc:                                              Laurie A. Burlingame