102 patients with suspected vasculogenic impotence were evaluated with color doppler sonography. Measurement of normal systolic and diastolic velocities were obtained from the cavernosal arteries of patients responding by a full erection after intra-cavernosal injection of 20 mg of Papaverine. A correlation with cavernosometry was obtained in 61 patients and with selective internal pudendal arteriography in 11. The 10 patients with abnormal arteriograms had a systolic velocity < 25 cm/sec. 13 out of the 15 patients with an end diastolic velocity > 5 cm/sec had a venous leak defined by a maintenance flow rate of erection during cavernosometry > 25 ml/mn. End diastolic velocity is an excellent index of the function of the veno-occlusive system, provided the systolic velocity remains at a normal value. In case of arterial insufficiency, a diastolic flow < 5 cm/sec is of no value and cavernometry is mandatory to detect a mixed arterio-venous impotence. The addition of color doppler sonography permitted a more rapid detection of vessels and an easily reproducible measurement of velocities which makes color doppler sonography an excellent screening test for examining patients with potential vasculogenic impotence.