Corpus cavernosograms and pressure flow dynamics were used to evaluate 28 impotent men. The rises in pressure during saline infusion and development of artificial erection were the criteria used to divide the men into three groups. The cavernosograms were graded as to filling of venous channels, staining of glans and spongiosum, completeness of filling, filling defects, and tunica thickening. The seven men who had the lowest rises in intracavernous pressure failed to develop erection and had the greatest evidence of prominent venous drainage. The seven men who developed artificial erection at 120 ml/min had the least evidence of venous drainage, while the remaining 14 men, who developed partial erection, had intermediate findings. Eight patients had abnormal arteriograms; two had no erection, four had partial erection, and two had full erection. Artificial erection can be induced in some impotent men. Prominent venous drainage will prevent artificial erection in some impotent men.