CRISPR Therapeutics (CRSP) 10-Q 2018 Q2 Quarterly report

Exhibit 32.1

CERTIFICATION 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 CRISPR Therapeutics AG (the “Company”) for the period ended June 30, 2018 as filed with the Securities and Exchange Commission on or about the date hereof (the “Report”), the undersigned officers of the Company hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to his or her knowledge:

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

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

/s/ Samarth Kulkarni

Samarth Kulkarni

Chief Executive Officer

(Principal Executive Officer)

August 7, 2018

/s/ Michael Tomsicek

Michael Tomsicek

Chief Financial Officer

(Principal Financial and Accounting Officer)

August 7, 2018