Objective:To analyze the effect of administering soybean extracts during pregnancy and breastfeeding on hormonal disturbances and impaired spermatogenesis in male rats b to mothers receiving soybean extract.Methods: Twenty-eight male rat puppies were divided into four groups: the control group (no treatment) and the groups male rat puppies whose mothers have been given soy extract of various doses (68.88 μg/mL, 137.76 μg/mL and 275.52 μg/mL). Those male rats were b to female rats given soybean extracts during their pregnancy and lactation until the age of one month. Analysis of the levels of LH, FSH and testosterone was performed by the ELISA technique. Testicular spermatogenesis was analyzed by histopathology.Results:FSH levels were significantly lower for all three doses of soy extract than those of the control group (P<0.05). FSH levels increased significantly in the group treated with the third dose of soybean extract relative to those of the first and second doses (P<0.05). LH levels were significantly lower for all three doses of soy extract than those of the control group (P<0.05). Testosterone levels were significantly lower for the third dose of soybean extract relative to those of the control group (P<0.05). With regard to histology of seminiferous tubules, it was found that the higher the dose of extract the more severe the constraints to spermatogenesis would be.Conclusion:Administration of soybean extract since the intrauterine period, during lactation and at the age of two months to male rats will lead to hormonal changes and impaired spermatogenesis.