Echo-color-doppler is a non invasive diagnostic technique which can provide data about arterial and venous vascular circle of the penis with greater precision than Doppler CW. In the tumescent phase after a PGE1 injection the systolic velocity (SV) reaches a rate higher than 25 cm/sec and the diastolic velocity (DV) higher than 2 cm/sec, resistance index (RI) > to 0.70 with evident colour marked from 1 to 3 KHz. In erection arterial flow decrease and SV is lower than 25 cm/sec with DV lower than 2 cm/sec or with negative values; RI < to 0.70 or negative. The data are confirmed by clinical investigation and traditional diagnostic exams in normal and pathological patients. Echo-color-doppler reduces invasive exams and acquires a primary position on the diagnostic scale of impotence.