The drug proskar (finasteride) belongs to 5 alpha-reductase blockers breaking the steps of prostatic adenoma pathogenesis. Proskar (Merck and Co. Inc., USA) was given to 38 patients with prostatic adenoma stage I and II (residual urine < 50 ml) admitted to urological clinic of the Moscow Medical Academy in 1993-1995. Daily dose was 5 mg. In patients with associated inflammation it was treated prior to proskar administration. To reject carcinoma, patients with elevated levels of prostatic specific antigen (< 4 ng/ml) were subjected to polyfocal biopsy of the gland. In any case, these patients received antiandrogens flutamide or androkur. Subjective response was achieved in 33 of 38 patients (86.8%). Better urination was reported in 29 patients (76.3%). Abdominal and transrectal ultrasonic scanning registered a decrease in the size of the prostate in 25 (65.8%) patients. Proskar was well tolerated, sexual disturbances occurred only in 2 patients. Proskar is effective in therapy of prostatic adenoma stage I. However, its intake must be long and regular, otherwise recurrent clinical symptoms and further growth of prostatic adenoma are possible.