A study was done in 21 men to identify individuals with venous leakage as a cause of impotence. Combined pressure flow measurement and cinecavernosography were performed before and after the injection of papaverine into the corpora. After papaverine injection, erections and/or higher pressures occurred at lower flow rates in all the men. The venous drainage of the corpora decreased or disappeared in most subjects while the corpora became larger and contained more contrast material. The findings suggest that an active venous obstructive mechanism is important during erection, can be induced by the administration of papaverine, and should be evaluated in impotent men.