The effect of intracavernous injection of papaverine (ICIP) has been investigated in 45 men: 6 normally potent volunteers, 10 psychogenic, and 29 organic impotent males. The first two groups obtained erections within 10 minutes, lasting from 1 to 4 hours, after injection of 80 mg of papaverine. Those belonging to the organic group experienced delayed, weaker and shorter erections, related to various degrees of arterial and/or venous and neurologic lesions. Haemodynamic and radiologic studies done concomitantly, showed a strong vasodilation in the penile arteries (even when pathologic) and a diminished outflow from the cavernous bodies. Subsequently, a pilot study was performed in a series of 63 patients suffering from various degrees of angiogenic impotence, in order to study the therapeutic effect of repeated intracavernous injections of papaverine completed by intracavernous infusion of heparinized saline. Erections improved significantly in 66% of the patients with a mean follow up of one year.