August 21, 2008

Repros Therapeutics Inc. Announces No Tumors in First Completed Proellex Animal Carcinogenicity Study

Repros Therapeutics Inc. (NasdaqGM:RPRX) today released the evaluation of the microscopic assessment of tissues from a six-month mouse study conducted to satisfy a portion of the FDA mandated two-species trials to demonstrate the lack of carcinogenic potential for new chemical entities. In this positive and negative controlled study, Proellex showed no microscopic evidence for tumor induction as compared to both controls. Proellex was tested at 10, 40 and 100 times the human dose in this well-recognized and -characterized study. Previously, the Company reported that the positive control, urethane, yielded easily identifiable tumors on gross necropsy while none were observed in the Proellex treated animals.

This mouse carcinogenicity study of Proellex was sponsored by Repros Therapeutics at BioReliance in Rockville, Maryland using a breed of mice bearing the rasH2 mutation. These rasH2 mice have been genetically manipulated making them primed for the development of tumors when treated with carcinogens. Male and female animals had been treated with daily doses of Proellex for 26 weeks and an evaluation was made as to whether cancers developed over that period of time when compared to a control material. Gross examination revealed no apparent indication of a tumorigenic response. All tissues were then assessed for microscopic evaluation. The assessment concluded that there were no treatment-induced hyperplastic or neoplastic changes in any of the Proellex treated groups. A final study report is in the process of being prepared for submission to the FDA.

Joseph S. Podolski commented, "We continue to be pleased with the excellent progress being made in our NDA program for Proellex. As anticipated, the lack of gross findings previously reported has been confirmed by microscopic evaluation."

About Repros Therapeutics Inc.

Repros Therapeutics focuses on the development of oral small molecule drugs for major unmet medical needs that treat male and female reproductive disorders.

Our lead drug, Proellex(R), is a selective blocker of the progesterone receptor and is being developed for the treatment of symptoms associated with uterine fibroids and endometriosis. We are also developing Proellex as a short course pre-surgical treatment for anemia associated with excessive menstrual bleeding related to uterine fibroids. There is no currently-approved effective long-term orally administered drug treatment for uterine fibroids or endometriosis. In the United States alone, 300,000 women per year undergo a hysterectomy as a result of severe uterine fibroids.

Our second product candidate, Androxal(R), is a single isomer of clomiphene citrate and is an orally active proprietary small molecule compound. We are developing Androxal for men with low testosterone and adult-onset idiopathic hypogonadotrophic hypogonadism ("AIHH") with concomitant plasma glucose and lipid elevations, all of which are components of Metabolic Syndrome. We are also developing Androxal for men of reproductive age with low testosterone levels who want to improve or maintain their fertility and/or sperm function while being treated for low testosterone.

Any statements that are not historical facts contained in this release are forward-looking statements that involve risks and uncertainties, including Repros' ability to raise additional capital in a timely manner and on acceptable terms or at all, Repros' ability to have success in the clinical development of its technologies, the timing of enrollment and release of data in such clinical studies and the accuracy of such studies, limited patient populations of clinical studies to date and the possibility that final data may not be consistent with interim data and such other risks which are identified in the Company's most recent Annual Report on Form 10-K and in any subsequent quarterly reports on Form 10-Q. These documents are available on request from Repros Therapeutics or at Repros disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

For more information, please visit the Company's website at