Abstract:The effects of anti-fertility EP-1 at the concentration of 1/20 000 on sex hormones, reproductive organs and reproductive behavior of male Mongolia gerbils were studied under the laboratory condition. One week treatment results had no significant differences in the concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and exogenous estradiol-17-β (E2) in serum by radioimmunoassay compared with the control. While the concentration of testosterone (T) was significantly lower than that of the control. The weight of seminal vesicle was obviously lower comparing with the control, but no distinct differences had been found in the weight of testis and epididymis. The mean deformity rate of sperms was (55.00±2.79)%, which was two-fold higher than that of the control at (32.00±2.36)%. The mean abnormal rate of the seminiferous tubules in the testis was (22.99±5.00)%, which is higher than that of the control at (4.21±1.18)%. The test mice in paired didn’t mate but only smelled mutually, and the frequency of smelling was lower than that of the control, and the frequency of fighting and attacking also decreased. The reproductive rate of the control was 55.6% while the experimental group was zero.