KAMANI, M.; MHABADI, J. A.; ATLASI, M. A.; SEYEDI, F.; KAMANI, E. & NIKZAD, H.Protective effect of alcoholic extract of garden cress seeds on the histopathological changes of the ventral prostate in streptozotocin diabetic rats. Int. J. Morphol., 35(3):1178Morphol., 35(3): -1184Morphol., 35(3): , 2017. SUMMARY:Diabetes mellitus is a common serious metabolic illness occurring worldwide that may lead to male infertility. Various plants have been used in the treatment of diabetes. In this study, the effect of garden cress (Lepidium sativum) seed extract on fasting blood sugar is assessed for its protective effect on histopathological changes in the ventral prostate gland of streptozotocine-induced diabetic rats. Fifty adult male Wistar rats were randomly selected into five groups. Group 1 was the control placebo group where rats received only 0.1 mL normal saline via gastric gavages. Rats in Group 2 received an intraperitoneal injection of STZ 60 mg/kg body weight and those with FBS >250 mg/dL were considered diabetic. In Group 3, diabetic rats received insulin (3 U/100 g body weight) while in Groups 4 and 5 diabetic rats received 0.1 ml of 200 and 400 mg/kg respectively of an ethanol extract of Lepidium sativum seeds by gavage daily. The prostate was removed and weighed before transfer to Bouin's solution for histological studies. Administration of the 200 and 400 mg/kg doses of Lepidium sativum seed extract increased epithelium height and decreased interstitial volume density and fibromuscular thickness of the prostate significantly. Also, the volume density of the epithelium, fibro muscular, lumen, and interstitial tissues were changed significantly. The results suggest that Lepidium sativum seed extract has beneficial effects as a protective agent against the detrimental effects of diabetes on the reproductive system of diabetic male rats.