To evaluate the efficacy and safety of intracavernous self-injection of phentolamine and papaverine for the treatment of impotence, 30 patients were enrolled in a prospective, randomized, double-blind, placebo-controlled cross-over study of papaverine and phentolamine versus normal saline. A total of 29 patients completed the study. The phentolamine plus papaverine combination resulted in erection in 24 patients (82.8 per cent) and no erection occurred after injection of saline. Of the patients 12 (41.4 per cent) experienced technical difficulties with the injection. Ecchymosis of the penis at the site of injection was common and 1 patient experienced priapism that resolved spontaneously. No other side effects occurred. Intracavernous self-injection with phentolamine and papaverine appears to be a safe and effective treatment of impotence but long-term effects must be determined.