Background: Environmental factors and hormonal disorders during prenatal life can impair the evolution and differentiation of fetus’s reproductive system. The aim of this study was to the examination of sperm quality and testis tissue in adult rats that had exposed to exogenous testosterone during their prenatal life. Materials & Methods: Pregnant rats divided into two experimental and control groups. In experimental group, pregnant rats daily were subcutaneously injected with 3 mg exogenous testosterone during gestational days 16-19, and controls received solvent. The reproductive system was examined in male offspring of these animals after puberty. Data analysis was performed by using the SPSS software (version 15). Distributions between groups are compared by using the Mann-Whitney test. Results: In the offspring of experimental group, motility and the number of sperm were significantly decreased (P<0.05). No morphological abnormality was observed in sperm in two groups. The numbers of sertoli cells, ratios of spermatocyte and round spermatid cells were significantly decreased in the offspring of experimental group (P<0.05). No significant difference was observed in seminiferous tubules diameter between the two groups. Serum testosterone levels were significantly decreased in offspring from experimental group (P<0.05). Conclusion: The present study showed that prenatal exposure to testosterone leads to decrease of sperm quality and changes in testis tissue in male rats, after puberty.