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 of Zonagen, Inc. (the "Company")
on Form 10-Q for the quarter ended June 30, 2003 as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), I, Joseph S.
Podolski, President and Chief Executive Officer of the Company, certify,
pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, that:

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.

Dated:  August 14, 2003                              By: /s/ Joseph S. Podolski
                                                     -------------------------
                                                     Joseph S. Podolski
                                                     President and
                                                     Chief Executive Officer
                                                     Zonagen, Inc.

A signed original of this written statement required by Section 906 has been
provided to Zonagen and will be retained by Zonagen and furnished to the
Securities and Exchange Commission or its staff upon request.