Abstract: Ninety two male rats were used. to study the effect of gossypol on the gonadal hormone levels. Rats were administered gossypol acetic acid orally at the dosage of 30mg/kg/day, six times per week, for 2,4 and 8 weeks. Serum testosterone, LH, FSH and testicular testosterone were determined by RIA. Results showed that at the end of 2,6 and 8 weeks of drug administration, serum testosterone levels were reduced-significantly, while serum LH levels were not changed. At the end of 8 weeks of gossypol treatment serum FSH level was elevated to approximately 4 times the control value. Organ weights and morphology of the testes were measured and examined. At the end of 8 weeks of treatment, the weights of testes, epididymis, seminal vesicles and ventral prostates were significantly reduced. Scoring was used to investigate the degree of damage of the testes after 8 weeks gossypol treatment. Severe damage was discernible in most of the seminiferous tubules of the treated rats. All the results pointed to they possibility that gossypol affected the function of Leydig cells.