Vascular origin accounts for more than 25% of cases of disturbances of erection. Venous pathology may explain the majority of erectile dysfunctions in patients with normal arterial anatomy. We have performed cavernography in 115 patients with monitoring of intracavernous pressure. Nocturnal plethysmography was recorded in all cases to prove the organic etiology of the erectile dysfunction. Cavernography was realized after puncture of both corpora cavernosa by two microcatheters (19-21 G). The intracavernous pressure was recorded through 1 of them and the contrast medium infused through the other. The contrast medium is infused at a rate of 80-120 ml/min. until the penis appears erect. The simultaneous recording of the intracavernous pressure then showed a rapid increase of the pressure curve followed by a stabilization at greater than or equal to 90 mHg. The flow to maintain the erection reach 1/3 of the flow needed to induce the erection. The venous leak is characterized by the absence of erection, no increase in intracavernous pressure and a rapid opacification of the vein. Artificial erection induced in impotent men allows to classify patients with vascular organic impotence into three categories: those with pure arterial insufficiency, those with pure venous leak, and patients with both.