SC TO-C

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   SCHEDULE TO
                                  (RULE 13E-4)

        TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

                                  ZONAGEN, INC.
                       (NAME OF SUBJECT COMPANY (ISSUER))

                                  ZONAGEN, INC.
                 (Names of Filing Persons (offeror and issuer))

                    Common Stock, par value $0.001 per share
                         (Title of Class of Securities)

                                   98975L 10 8
                      (CUSIP Number of Class of Securities)

                               Joseph S. Podolski
                      President and Chief Executive Officer
                                  Zonagen, Inc.
                        2408 Timberloch Place, Suite B-10
                           The Woodlands, Texas 77380
                                 (281) 719-3400
                 (Name, address, and telephone numbers of person
               authorized to receive notices and communications on
                            behalf of filing persons)

                                    Copy to:

                                Jeffrey R. Harder
                                Andrews Kurth LLP
                     10001 Woodloch Forest Drive, Suite 200
                           The Woodlands, Texas 77380
                                 (713) 220-4801

|X|  Check the box if the filing relates solely to preliminary communications
     made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

                  [ ] third-party tender offer subject to Rule 14d-1.

                  |X| issuer tender offer subject to Rule 13e-4.

                  |X| going-private transaction subject to Rule 13e-3.

                  [ ] amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting results of
the tender offer: [ ]

ITEM 12.     EXHIBITS.

      (a)(1) Press Release Issued on November 3, 2003 Updating Proposed Tender
             Offer.

                                  EXHIBIT INDEX

  Exhibit
  Number                           Description
  -------                          -----------
  (a)(1)          Press Release Issued on November 3, 2003 Updating Proposed
                  Tender Offer.

EX-99.A.1

                                                                  EXHIBIT (a)(1)

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


FOR IMMEDIATE RELEASE


        ZONAGEN PROVIDES UPDATE ON PROPOSED "DUTCH AUCTION" TENDER OFFER

         (The Woodlands, Texas) - November 3, 2003 - Zonagen, Inc. ("Zonagen")
(NASDAQ: ZONA) is updating its previously announced "Dutch Auction" tender offer
to purchase up to 9,836,065 shares of its outstanding common stock at a purchase
price per share no greater than $2.10 nor less than $1.83. Pursuant to SEC
rules, Zonagen will change the provision regarding preferential purchases such
that if more shares are tendered than Zonagen can purchase for an aggregate
purchase price of $18 million, Zonagen will first purchase all of the shares
held by stockholders holding less than 100 shares and will then purchase the
remaining shares on a pro rata basis. It had originally announced that this
number would be 1,000 shares.

         In addition, to assist its stockholders in understanding the range set
in this tender offer, Zonagen would like to inform its stockholders that the
minimum price of $1.83 is based on the estimated cash liquidation value of
Zonagen's common stock, based on Zonagen's cash and cash equivalents at
September 30, 2003, estimated liquidation expenses and reserves and our
currently outstanding shares and in-the-money options.

         Neither Zonagen nor its Board of Directors make any recommendation as
to whether stockholders should tender their shares. Stockholders must make their
own decision as to whether to tender their shares and, if so, how many shares to
tender and at what price.

         ZONAGEN URGES ALL STOCKHOLDERS TO READ THE OFFER TO PURCHASE AND THE
RELATED DOCUMENTS FILED WITH SUCH OFFER TO PURCHASE WHEN IT IS AVAILABLE BECAUSE
IT WILL CONTAIN IMPORTANT INFORMATION. STOCKHOLDERS MAY OBTAIN A COPY OF THE
OFFER TO PURCHASE AND RELATED DOCUMENTS FOR FREE AT THE COMMISSION'S WEB SITE AT
WWW.SEC.GOV. ZONAGEN WILL ALSO PROVIDE AT NO CHARGE A COPY OF THE OFFER TO
PURCHASE AND ANY OTHER RELATED DOCUMENTS TO ANY STOCKHOLDER WHO REQUESTS SUCH
DOCUMENTS BY CONTACTING ZONAGEN AT (281) 719-3400.

         ABOUT ZONAGEN

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

         THIS PRESS RELEASE CONTAINS FORWARD-LOOKING STATEMENTS CONCERNING
ZONAGEN'S TENDER OFFER. FACTORS THAT MAY AFFECT FUTURE RESULTS INCLUDE THE
RESPONSE OF STOCKHOLDERS TO THE TENDER OFFER, FUTURE GENERAL AND SECTOR ECONOMIC
AND MARKET CONDITIONS, THE IMPACT OF GOVERNMENT REGULATION OF TENDER OFFERS AND
DECISIONS OF THE BOARD OF DIRECTORS. PLEASE REVIEW REPORTS FILED BY ZONAGEN,
INCLUDING THE FORTHCOMING OFFER TO PURCHASE WHICH WILL BE FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION, FOR ADDITIONAL INFORMATION CONCERNING
FACTORS THAT COULD AFFECT ZONAGEN'S BUSINESS.