EXHIBIT 99.1



Contact:
Joe Podolski, President and CEO
podolski@zonagen.com
281-719-3447
FOR IMMEDIATE RELEASE


                 ZONAGEN REPORTS BREAST CANCER TUMOR INHIBITORY
                    EFFECTS OF PROGENTA(TM) IN ANIMAL MODEL

         (The Woodlands, Texas) - March 30, 2004 - Zonagen, Inc. (Nasdaq: ZONA)
announced that Dr. Ronald Wiehle, the Company's Director of R&D, is presenting
today data generated at Zonagen in collaboration with scientists at the
University of Illinois-Chicago that indicate the potential for Progenta(TM) for
the treatment of breast cancer. The data is being presented at the 2004 Annual
Meeting of the American Association for Cancer Research being held in Orlando,
Florida.

         The poster presentation elaborates upon the Company's recent finding
that Progenta(TM) shows significant activity against hormone-dependent breast
cancer induced in rats by DMBA. DMBA is a tumor-inducing agent used in a
well-accepted breast cancer tumor model. In the study, rats were given DMBA at
50 days of age and entered randomly into treatment groups when the lead tumor
reached 12 mm in size. Groups of 10-13 rats were treated for 28 days with
vehicle (oil) or with varying doses of Progenta(TM) with or without
progesterone. Progenta(TM) reduced the size of established tumors significantly
and prevented the appearance of new tumors over the course of the treatment
period. The strong anti-tumor effects seen with Progenta(TM) correlated with
suppression of growth and increased apoptosis, or programmed cell death, by
immunohistochemistry. Whereas progesterone enhanced tumor growth, Progenta(TM)
was very effective in promoting tumor regression.

         This work was funded via a Phase I Small Business Research grant
(SBIR). The Company is in the process of requesting additional government
funding through a Phase II grant to further elucidate these effects before
considering a human clinical program for the indication.

         In addition, Zonagen is currently preparing the necessary documentation
to seek approval to begin a European Phase I/II study of Progenta(TM) for the
treatment of uterine fibroids.

         ABOUT ZONAGEN

         Zonagen is engaged in the development of pharmaceutical products that
address diseases and conditions associated with the human reproductive system.

Any statements that are not historical facts contained in this release are
forward-looking statements that involve risks and uncertainties including
Zonagen's ability to have success in the clinical development of its
technologies, Zonagen's ability to raise additional capital on acceptable terms
or at all, uncertainty relating to Zonagen's patent portfolio, Zonagen's ability
to have success in meeting governmental regulations and the costs and time
required to meet such regulatory requirements, manufacturing uncertainties
related to Progenta(TM), the Company's ability to remain listed on Nasdaq, and
such other risks identified in Zonagen's Annual Report on Form 10-K for the year
ended December 31, 2003, as filed with the Securities and Exchange Commission
(SEC). These documents are available on request from Zonagen or at www.sec.gov.
Zonagen disclaims any intention or obligation to update or revise any
forward-looking statements, whether as a result of new information, future
events or otherwise.