Abstract： AIM:To study the relation between female gonad toxicity of methoxychlor(MXC)on rats, subchronie methoxyehlor effect on the female gonad was carried out. METHODS:Forty female SD rats were randomly divided into 4 groups, 4 different dose levels[0, 16, 32 and 64 mg/(kg·d)MXC]were injected intraperitoneally accordingly for 20 d. Vaginal smears of rats were performed to determine estrous cycle. The rats were sacrificed on the day of estrus stage. Body weights, estrus stage, organ weights and organ coefficients of ovary were observed. Uterine tissue and ovary were prosessed for histologic examination. RESULTS:①Increasing of body weight was not different between 4 groups after treatment. ②Estruation was prolonged in MXC 32 and 64 mg groups, periodicity decresed accordingly. ③ Organ weights and organ coefficients of ovaries in rats treated with MXC 32 and 64 mg groups were significantly different from the control group. ④ Numbers of atresic follicle were significantly increased in both the MXC 32 and 64 mg groups, the atresic rate of secondary follicle was significantly increasd. CONCLUSION:① MXC could result in prolonged estruation circle and increased number of atresic follicle. ② No significant influence on female gonads toxicities was found in low-dose group.