Enzo Biochem Says U.S. Appeals Court Overturns Decision and Reinstates Company's Gonorrhea Patent.

Business Editors & Health/Medical Writers

Enzo's Infringement Suit Against Five Defendants to Proceed Before

Trial Court

Enzo Biochem, Inc., (NYSE:ENZ) said today that the U.S. Court of Appeals for the Federal Circuit yesterday issued a ruling that now reverses a summary judgment issued earlier by a Federal District Court invalidating an Enzo gonorrhea detection patent and reinstating Enzo's suit alleging patent infringement against Gen-Probe Incorporated and four other defendants, returning the case to the trial court.

The Court of Appeals on April 2, 2002 had previously affirmed the grant of summary judgment involving Enzo's U.S. Patent No. 4,900,659, which is directed to nucleic acid probes for the detection of the bacteria that cause gonorrhea. The U.S. District Court for the Southern District of New York had declared the `659 patent was invalid for lack of written description of the claimed invention. Following the earlier two-to-one decision by the Court of Appeals that had upheld the trial court, Enzo filed a petition for a rehearing and yesterday's decision was the result of that filing.

"Having considered Enzo's petition for rehearing and the defendant's response, we have determined that our prior decision that a deposit may not satisfy the written description requirement was incorrect," the three members of the Appeals Court unanimously declared in vacating the prior decision.

In yesterday's decision, they granted Enzo's petition for rehearing, vacated the prior decision and reversed the district court's grant of summary judgment that Enzo's claims are invalid for failure to meet the written description requirement. Citing genuine issues of material fact that exist regarding satisfaction of the written description requirement, the case was returned for further proceedings before the trial court. No trial was ever held.

"We at Enzo are obviously pleased and appreciative of the Appeals Court's reconsideration of our position." said Elazar Rabbani, Ph.D, Chairman and CEO of Enzo. "We look forward to the proceedings with our case, and we are confident our original claim of patent infringement will be upheld."

In addition to Gen-Probe Incorporated, the other defendants named in Enzo's suite included Chugai Pharma U.S.A., Inc., Chugai Pharmaceutical Co., Ltd., bioMerieux, Inc., and Becton Dickinson and Company.

About Enzo:

Enzo Biochem is engaged in the research, development and manufacture of innovative health care products based on molecular biology and genetic engineering techniques, and in providing diagnostic services to the medical community. The Company's proprietary labeling and detection products for gene sequencing and genetic analysis, with approximately 200 patents worldwide, are sold to the life sciences market throughout the world. The Company's therapeutic division is conducting clinical trials for HIV-1-infected patients and for patients infected with hepatitis B and hepatitis C viruses. The Company also holds a patent covering a method and materials for correcting point mutations or small insertions or deletions of genetic material that would allow for editing and correcting certain abnormalities in genes.

Except for historical information, the matters discussed in this news release may be considered "forward-looking" statements within the meaning of Section 27A of the Securities Act of 1933, as amended and Section 21E of the Securities Exchange Act of 1934, as amended. Such statements include declarations regarding the intent, belief or current expectations of the Company and its management. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve a number of risks and uncertainties that could materially affect actual results. The Company disclaims any obligations to update any forward-looking statement as a result of developments occurring after the date of this press release.