Exhibit 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER

PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Axcella Health Inc. (the “Company”) for the quarterly period ended June 30, 2019 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), each of the undersigned, William R. Hinshaw, Jr., Chief Executive Officer, President and Director of the Company, and Thomas Leggett, Senior Vice President of Finance and Chief Financial Officer of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of his knowledge:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: August 12, 2019	By:	/s/ William R. Hinshaw, Jr.
		William R. Hinshaw, Jr.President, Chief Executive Officer and Director (Principal Executive Officer)

Date: August 12, 2019	By:	/s/ Thomas Leggett
		Thomas LeggettSenior Vice President of Finance, Chief Financial Officer (Principal Financial Officer)