Exhibit 32.1

SECTION 1350 CERTIFICATION

Each of the undersigned, Martin J. Duvall, Chief Executive Officer of Tocagen Inc., a Delaware corporation (the “Company”), and Mark Foletta, Chief Financial Officer of the Company, do 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 the best of his knowledge (1) the quarterly report on Form 10-Q of the Company for the quarterly period ended March 31, 2019, as filed with the Securities and Exchange Commission on the date hereof (the “Report”) and to which this Certification is attached as Exhibit 32.1, 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. 

/s/ Martin J. Duvall

Name: Martin J. Duvall

Title: Chief Executive Officer (Principal Executive Officer)

Dated: May 7, 2019

/s/ Mark Foletta

Name: Mark Foletta

Title: Chief Financial Officer (Principal Financial Officer)

Dated: May 7, 2019

This certification accompanies and is being “furnished” with this Report, shall not be deemed “filed” by the Company for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to liability under that Section and shall not be deemed to be incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date of this Report, irrespective of any general incorporation language contained in such filing. A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.