Abstract: ObjectiveTo investigate the effect of cadmium(Cd)on sperm production and level of sexual hormone in rat testis in order to provide the scientific support for the study on mechanism of sperm toxicity cadmium.MethodsForty male SD rats were assigned randomly to four groups and were administrated with various doses of cadmium chloridedaily dose was respectively 0,0.25,0.5,1.0 mg Cd²⁺/(kg·bw)for 7 days in intraperito neal injection,then the testis weight,ratio of testis to body,caudal epididy mides testicular sperm count and daily sperm production were measured.The level of testosterone orestrogen in both serum and testis tissue were measured by radioimmunoassay.ResultsThe weight of leftward,dextral testis and ratio of testis to body in the middle and high dose group were significantly lower than those of the control group.The caudal epididy mides testicular sperm count of the low,middle and high dose group(538±151)×10⁶,(242±143)×10⁶,(39± 4)×10⁶were significantly lower than those of the control group in dos-edependent manner(727±242)×10⁶,The daily sperm production of the middle and high dose group(6.2±4.8)×10⁶/g,(4.0±3.0)×10⁶/gwere significantly lower than those of the control group(12.7±6.4)×10⁶/g.The testosterone level of both serum(0.8±1.1)ng/mland testis tissue(11.6±3.5)ng/mlin the middle dose group were significantly lower than those of the contr ol groupserum:(3.2 ±2.7)ng/ml,tissue:(20.9±3.8)ng/ml.There was no difference in estrogen level of both serum and testis tissue in each group.ConclusionCadmium causes obvious toxicity in testis and markedly decrease sperm amount.Decreased testosterone level is one of mechanisms underly ing sperm production function impaired by cadmium.Estrogen production in male rats is not impaired and estrogen level appears no linked with weaken function of sperm production caused by cadmium.