Introduction: Sesame seeds contain large amounts of antioxidants and phytoestrogens, and it has been shown that the leaf extract of this plant may have some beneficial effects on the reproductive parameters of male rats. Thus we tested the effects of the sesame oil on these parameters of reproductivity in male rats. Materials and Methods: Fifteen mature male Wistar male rats were divided into the control and sesame oil groups. For eight weeks the control and sesame oil groups were fed the basic rat diet and basic rat diet supplemented with 5% sesame oil respectively. Following blood collection and euthanasia the epididymal sperm were counted, the morphology of testes was accessed, and leydig, sertoli, spermatogonia and spermatocyts cells were counted in histological sections of the testes. The level of testosterone and estradiol 17- β were measured. Results: Consumption of 5% sesame oil compared to control group, decreased blood glucose and increased the epididymal sperm count and progressive motility and the number of spermatogonia of seminiferous tubule (P<0.05), but had no effect on weight and testicular morphology. Conclusion: This study showed that the sesame oil consumption improves some reproductive parameters, which may be related to the antioxidative and phytostrogenic properties of the sesame oil or insulin action improvement.