Objective To study post-testis targets related to male contraception and infertility caused by dutasteride treatment on rat sperm maturation and fertility.Methods Rats were treated with 20 and 40 mg/kg/d dutasteride for consecutive 14 days.Each male rat was paired with 2 female rats and the reproductive indices were assessed.Sperm motility and morphology were analyzed by a computer-assisted sperm analysis system.The sperm survival rate was assessed by SYBR-14 and PI fluorescent staining.Serum dehydrotestosterone(DHT) and T of rats were detected by ELISA.Histological examination of testis and epdidymis was conducted by HE staining.Results The DHT level,sperm motility and the pregnancy index by treatment were all significantly decreased(P<0.05 or 0.01),while the abnormal sperm rate was increased(P<0.05).But there was no difference in serum T level between dutasteride treated and control males(P>0.05).The histology of testis and epididymis was also unaffected by treatment.Conclusions Dutasteride can induce infertility in male rats through inhibiting serum DHT level and interfering with epididymal sperm maturation,which may open a new approach for research on male contraception and fertility.