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

Pursuant to 18 U.S.C. Section 1350, the undersigned Officer of Opexa Therapeutics, Inc. (the “Company”), hereby certifies, to such officer’s knowledge, that the Company’s Quarterly Report on Form 10-QSB for the quarter ended June 30, 2006 (the “Report”) fully complies with the requirements of Section 13(a) or Section 15(d), as applicable, of the Securities Exchange Act of 1934 and that the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

By: /s/ David B. McWilliams

David B. McWilliams, CEO

Date: August 11, 2006

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