September 5, 2019

Briggs W. Morrison
Chief Executive Officer
Syndax Pharmaceuticals, Inc.
Building D, Floor 3
35 Gatehouse Drive
Waltham, MA 02451

       Re: Syndax Pharmaceuticals, Inc,
           Registration Statement on Form S-3
           Filed August 30, 2019
           File No. 333-233564

Dear Dr. Morrison:

       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 Tonya K. Aldave at (202) 551-3601 with any questions.



                                                            Sincerely,

                                                            Division of
Corporation Finance
                                                            Office of
Healthcare & Insurance
cc:    Jaime L. Chase, Esq.