EXHIBIT 99.1


FOR IMMEDIATE RELEASE


  ZONAGEN TO COMMENCE EUROPEAN STUDY OF PROGENTA IN WOMEN WITH UTERINE FIBROIDS


THE WOODLANDS, Texas--(BUSINESS WIRE)--June 29, 2004--Zonagen, Inc.
(Nasdaq:ZONA)(PCX:ZNG) today announced that it will initiate a European Phase
I/II study of its lead program Progenta(TM) for the treatment of uterine
fibroids. The announcement was made following the Company receiving notification
from both institutional and governmental regulatory agencies regarding the
acceptability of the trial's design and preclinical data package. The study will
be conducted in Warsaw, Poland.

Uterine fibroids are common benign tumors of the uterus. They grow from the
muscular wall of the uterus and are made up of muscle and fibrous tissue. In
some women, uterine fibroids may cause heavy bleeding, pelvic discomfort and
pain, and create pressure on other organs. These symptoms may require treatment.
As many as 70% of all women have uterine fibroids. While the majority usually
have no symptoms, 1 in 4 end up with symptoms severe enough to require
treatment. In the United States, roughly 600,000 hysterectomies are performed
annually. Of these, a third or more are due to uterine fibroids. The medical
expenses associated with hysterectomies account for over five billion dollars of
annual spending.

The study that Zonagen is undertaking is being conducted incorporating Good
Clinical Practice (GCP) guidelines and has been contracted with a U.S. clinical
research organization (CRO). This study is the first human experience for
Progenta(TM). Several animal studies, including a long-term (9-month) primate
study, have been previously conducted exploring both the safety and activity of
the drug. The compound was one of several compounds licensed from the National
Institutes of Health (NIH) in 1999. The drug, named Progenta(TM), was selected
as a lead candidate following numerous studies conducted by both the NIH and
Zonagen.

The study will enroll a total of 30 women diagnosed with uterine fibroids. The
women will be referred to the trial by several gynecological practices in
Warsaw. They will be randomized into one of five parallel groups; placebo, three
different doses of Progenta(TM), and a positive control group consisting of an
approved gonadotropin releasing hormone agonist (GnRHa). GnRHa's are the current
gold standard of drug therapy for the indication and used most frequently prior
to hysterectomy. The placebo and Progenta(TM) groups will be blinded. The study
consists of three phases. Day 1 dosing will be followed for both initial safety
and pharmacokinetics. Following a one week washout and safety assessment, women
will take the drug for an additional 30 days after which time they will be
readmitted into the clinic to evaluate steady state pharmacokinetics, effects on
fibroid size, bone mineral density and hemoglobin. Women showing positive
effects on fibroid volume and hemoglobin without adverse reactions will be
allowed to continue in the trial for an additional two months. Women not
experiencing a benefit with the study drug will be allowed to switch to the
GnRHa for the duration of the study. At the end of the study, women on
Progenta(TM) will be evaluated for changes in bone mineral density, hemoglobin
levels and fibroid size and compared against the changes experienced by the
positive control group dosed with a GnRHa.

The Company believes it may have reportable data from the trial by yearend 2004.
Zonagen has also engaged a CRO to prepare for a pre-IND meeting it plans to hold
with the FDA later this year to discuss a U.S. program for Progenta(TM). At a
later date, Zonagen also plans to test the potential of Progenta(TM) in the
treatment of endometriosis. The safety data from this first study should be
directly applicable to the endometriosis program.

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 but
not limited to Zonagen's ability to have success in the clinical development of
its technologies, the reliability of clinical trials conducted in non-US
jurisdictions, 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.


    CONTACT: Zonagen, Inc., The Woodlands
             Joseph S. Podolski, 281-719-3447

     SOURCE: Zonagen, Inc.