SUMMARY:Sesamin is a major lignan constituent of sesame seed and considered as a key factor in a number of beneficial effects on human health. Sesame leaves intake improve and increase epididymal spermatocytes reserve in adult male sprague dawley rat. The present study was aimed to investigate the effects of contain sesame seed on epididymis histologhical structure. Thirty adult male rats were divided into two groups of 15 rats each. The regimen group received diet containing 30% sesame seed, while the control group received diet along 12 weeks. The right epididymis were removed and minced into several pieces on a specimen bottle containing normal saline for some few minutes to allow the sperms to become motile and swim out and sperm parameters were analyzed. Left epididymis were divided into three sections and fixed into bouin,s solution for further investigation. Serum FSH and LH concentration were estimated by ELISA technique, Testosterone concentration was done by using Chemo-Luminance method. The body weight gained during the treatment period did not differ significantly among groups. The mean epididymal sperm motility and count of the experimental group was significantly higher than control group. LH levels significantly increased in experimental group compared to controls but significant changes in FSH and testosterone levels were not observed in both groups. The results obtained showed that the mean epididymal diameter of the tubular, lumen and epithelium in three parts were not significant in two groups. It can be concluded that sesame seed improves sperm parameters (motility and count) and also can increase LH. But diet contains sesame seed did not affect on epididymal tissue and body weight.