March 5, 2020

Alison Lawton
Chief Executive Officer
Kaleido Biosciences, Inc.
65 Hayden Avenue
Lexington, MA 02421

       Re: Kaleido Biosciences, Inc.
           Registration Statement on Form S-3
           Filed March 2, 2020
           File No. 333-236804

Dear Ms. Lawton:

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

        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 Ada D. Sarmento at 202-551-3798 with any questions.


                                                            Division of
Corporation Finance
                                                            Office of Life
cc:    Laurie A. Burlingame, Esq.