November 15, 2018

Jeffrey S. Hatfield
Chief Executive Officer
Zafgen, Inc.
175 Portland Street, 4th Floor
Boston, Massachusetts 02114

       Re: Zafgen, Inc.
           Registration Statement on Form S-3
           Filed November 9, 2018
           File No. 333-228328

Dear Mr. Hatfield:

       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 Irene Paik at 202-551-6553 with any questions.



                                                            Sincerely,

                                                            Division of
Corporation Finance
                                                            Office of
Healthcare & Insurance
cc:    Danielle M. Lauzon - Goodwin Procter LLP