Arteriography of the penile vasculature was performed after intracavernous injection of prostaglandin E1 in five patients. Penile tumescence was obtained in three patients with a dose of 10 micrograms and in the other two patients with a dose of 20 micrograms. Mean duration of penile tumescence was 1 h 36 min. Visualization of the penile vasculature was adequate in all patients. Local pain was a minor side effect in one patient. These preliminary results suggest that prostaglandin E1 might represent an alternative for papaverine in the angiographic study of male impotence.