Penile revascularization for cases of arteriogenic impotence is based on the assumption of hemodynamically relevant connections between the dorsal penile and cavernous arteries. In 325 clinically impotent patients color-coded duplex sonography was performed with the penis flaccid and tumescent after intracavernous injection of 10 micrograms prostaglandin E1. We measured peak flow velocity, end diastolic flow velocity and resistance in the dorsal arteries, deep cavernous arteries and connections perforating the tunica albuginea between the 2 systems. Of our patients 14% had at least 1 such anastomosis with a peak flow velocity exceeding 25 cm. per second after stimulation. Peak flow velocities less than 20 cm. per second were noted only in arteriogenically impotent patients, while those exceeding 25 cm. per second without later rigid erection occurred only in patients with venous occlusive dysfunction and end diastolic flow velocity exceeded 5 cm. per second. We conclude that penile revascularization should be contemplated only if hemodynamically relevant connections are detected, peak flow velocity in the cavernous arteries is less than 20 cm. per second and end diastolic flow velocity is less than 5 cm. per second.