Abstract: After 3 weeks administration of 100mg clomiphene daily four infertile men showed that the mean LH basal level（from 18.6+0.2 to 54.7+0.6 IU/L） and LH pulse frequency （from 3.5±0.1 to 6.3±0.3 pulses/8h） were significantly higher than that in control peroid （both p＜0.01）. The amplitude was also increased （from 15.8±0.5 to 22.6±0.3 IU/L）, but not significantly enough （0.05＜P＜0.10）. The foregoing data reflected a remove of feedback inhibition of estrogen, and suggested that the estrogen played an important regulation role on gonadotropin secretion in male. The site of action was mainly in the hypothalamus.