Duplex and color Doppler sonography were used to assess the vascular status of 240 impotent patients. The tests were performed before and after intracorporal injection of a standard dose of a vasoactive mixture and measurements were done both at the crura and at the midshaft of the penis. Particular care was taken in the evaluation of cavernosal arteries diameter, wall pulsatility, morphology of spectral waveform, blood flow acceleration, systolic and diastolic flow velocity and flow volume. Resistance and pulsatility indexes of the cavernosal arteries were also measured. Flow along the deep dorsal vein was quantified when possible. Cavernosal artery peak systolic flow velocity, flow volume and acceleration were the best indicators of arterial penile circulation. Persistently elevated (> 10 cm/s) diastolic flow in the cavernosal arteries positively correlated with a diagnosis of venogenic impotence obtained by dynamic infusion cavernosometry--cavernosography in almost 80% of cases. Duplex and color Doppler sonography permit to thoroughly evaluate cavernosal arteries function and seem to have a promising role in the study of the veno-occlusive mechanism of the corpora cavernosa.