March 16, 2004

POLYDEX ANNOUNCES THAT CONRAD
HAS INITIATED CONTRACEPTIVE CLINICAL TRIALS OF USHERCELL WITH FUNDING FROM THE BILL AND MELINDA GATES FOUNDATION

ADDITIONAL INTERNATIONAL TRIAL PREPARATIONS UNDERWAY TO ASCERTAIN
EFFECTIVENESS OF USHERCELL AS A TREATMENT OF BACTERIAL VAGINOSIS

Toronto, Ontario, March 16, 2004 -- Polydex Pharmaceuticals Limited (NASDAQ:POLXF) (BSE:PXL) is pleased to provide this clinical trial update on Ushercell, its leading human pharmaceutical compound, envisioned for topical vaginal use primarily in the prevention of transmission of AIDS and other sexually transmitted diseases, as well as unplanned pregnancies. Two phase II contraceptive clinical studies were recently initiated by CONRAD and Family Health International. The studies will be conducted by the California Family Health Council in Los Angeles, CA, and their satellite clinical sites.

In a press release dated January 21, 2004, the Company announced the commencement of a non-comparative contraceptive effectiveness trial for Ushercell, and is pleased to announce that a further Phase II comparative contraceptive efficacy study of Ushercell was initiated in February. One hundred fifty heterosexual couples desiring pregnancy, but willing to postpone conception by one menstrual cycle, will be randomized between the placebo gel and Ushercell groups. The study is expected to be complete by the end of the year, with a report issued in 2005.

Ushercell, a contraceptive gel with antimicrobial properties, enjoys continued support from the prestigious research group CONRAD, advancing this compound through extensive safety and tolerance clinical trials, while providing the necessary funding. Funds from the Bill & Melinda Gates Foundation are being provided to CONRAD for the phase II clinical studies and supplies.

CONRAD has provided the FDA with several clinical and non-clinical updates pursuant to the Development Plan for Ushercell. One hundred thousand individual-dose units of Ushercell have been manufactured to supply the contraceptive efficacy trials.

Additionally, Management intends to initiate funding of a new research program into the possible use of Ushercell as a treatment for Bacterial Vaginosis. This research program was recommended in a report published by an international team of researchers, led by Dr. Jose Simoes and Dr. Lourens Zaneveld at the Department of Obstetrics and Gynecology, State University of Campinas, Sao Paulo, Brazil, and Rush-Presbyterian-St. Luke's Medical Center in Chicago, Illinois, with additional support from the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), Brazil, and continued support from Ushercell's leading research team at CONRAD. The research was conducted to evaluate how Ushercell affected the growth of G. vaginalis and anaerobes commonly associated with Bacterial Vaginosis.

The in vitro research resulted in a report, (Simoes J et al. Antimicrobial Agents and Chemotherapy, 46(8): 21692-2695, 2002) which indicated that Ushercell is effective at inhibiting bacteria commonly associated with Bacterial Vaginosis. BV, one of the most common vaginal disorders among reproductive-age women, arises when the normal balance of "good" and "bad" bacteria in the vagina goes awry, and harmful bacteria are allowed to thrive. The cited report included assessment of concerns that regular use of vaginal microbicides could disrupt this balance and enhance women's odds of contracting BV, and concluded that the use of Ushercell eliminated that concern, prompting recommendations for further testing of Ushercell as a treatment for BV, as well as a prevention method.

The progress in the development of microbicides will be reviewed by leading scientists and developers from around the world at a biennial event, Microbicides 2004, to be held during the last week of March 2004, in London England. Researchers from the Ushercell development team at CONRAD and Mr. George Usher, President and CEO of Polydex, will be in attendance at that conference.

Polydex Pharmaceuticals Limited, based in Toronto, Ontario, Canada, is engaged in the research, manufacture and marketing of biotechnology-based products for the human pharmaceutical market, and also manufactures bulk pharmaceutical intermediates for the worldwide veterinary pharmaceutical industry. Please visit our updated website at www.Polydex.com

Note: This press release may contain forward-looking statements, within the meaning of the United States Securities Act of 1933, as amended, and the United States Securities Exchange Act of 1934, as amended, regarding Polydex Pharmaceuticals Limited. Actual events or results may differ materially from the Company's expectations, which are subject to a number of known and unknown risks and uncertainties including but not limited to changing market conditions, future actions by the United States Food and Drug Administration or equivalent foreign regulatory authorities as well as results of pending or future clinical trials. Other risk factors discussed in the Company's filings with the United States Securities and Exchange Commission may also affect the actual results achieved by the Company.

CONTACT:
Polydex Pharmaceuticals Limited
George G. Usher, President
(416) 755-2231
or e-mail: gu-dextran@rogers.com

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