Benign prostatic hyperplasia (13P11) is a hyperplastic process of the strontal and epithelial cells of the prostate due to effect of male sex hormone testosterone. Testosterone is the main male sex hormone, responsible for growth of sexual character and accessory sex organs. Despite its effectiveness as an male sex hormone, it causes benign prostatic hyperplasia (BM resulting in urinary dysfunction. On the other hand, finasteride. a 4-azastroid, inhibits the hyperplastic effect of testosterone and benign prostatic hyperplasia. The objective of the study was to observe the effects of finasteride on the stroma of testosterone induced prostatic hyperplasis in long Evans rats. This experimental study was carried out in the Department of Anatomy, Sir Salimullah Medical College, Dhaka from January to December 2006. Total 45 matured male long Evans rats of age 8-10 weeks and weighing 200-300 gm were used in this study. They were divided into three equal groups. Group A was vehicle (olive oil) control group, Group 13 was testosterone treated group and Group C was testosterone and finasteride treated group. The rats were sacrificed on the eleventh day. It was concluded that finasteride is an effective drug that successfully inhibits the testosterone induced prostatic hvperplasia.