In our three-year experience with the use of flutamide for the treatment of carcinoma of the prostate, 20 patients with previously untreated stage D carcinoma of the prostate were enrolled in a 12-week double-blind study. Seven patients received 1.5 gm of flutamide daily, seven patients received 0.75 gm of flutamide daily, and six patients received 1.0 mg of diethylstilbestrol daily. Two patients receiving flutamide did not complete the 12-week study. Six patients receiving flutamide and three patients receiving diethylstilbestrol had objective evidence of improvement. Of the patients receiving flutamide, 50% were alive at one year, and 43% were alive at two years. Three of the original 14 patients started on flutamide are alive at 36, 33, and 24 months. In addition, we continued clinical evaluation of flutamide as an open study, enrolling six other patients (four with stage D and two with stage C carcinoma of the prostate). All except one of these patients had received previous hormonal therapy. At present, four are still being followed up at 13, 15, 20 and 24 months, demonstrating that flutamide can give positive results to some patients whose condition is deteriorating despite diethylstilbestrol therapy.