Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statement on Forms S-8 (No. 333-205253 and 333-210171) and Form S-3 (No. 333-216735) of Seres Therapeutics, Inc. of our report dated March 8, 2018 relating to the financial statements, which appears in this Form 10-K.  

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

March 8, 2018