The efficacy of papaverine and phenoxybenzamine as a pharmacological treatment of impotence was compared in a double blind, crossover, placebo controlled trial. Thirty-four impotent men received intra-cavernosal injections of papaverine (60 mg), phenoxybenzamine (6 mg) or normal saline (10 ml) at monthly intervals. Observations by EJK up to 45 minutes after injection demonstrated that papaverine caused full erections in 35% of men and partial erections in 62%. Phenoxybenzamine injection resulted in full erections in 20% of men and 62% had partial erections. The differences were not significant. Despite 82-97% of patients attaining some degree of erection in the clinical setting only six of the patients decided to use this mode of treatment for more than three months. Sexual function during the month after injection was better with either drug when compared with placebo.