Changes in blood flow to the pelvis were monitored by measurement of penile blood pressures before and after 38 aortoiliac vascular reconstructions. An increase in penile pressure was noted in 14 patients (37%), a decrease was seen in eight patients (21%), and no change occurred in 16 patients (46%). These changes could have been predicted by matching arteriograms to the surgical procedure performed. Preoperative impotence was present in 27 patients (17%). In this group a postoperative increase in penile pressure was associated with restoration of erectile capability in eight of 11 patients. Only one of 10 patients with an unchanged penile pressure regained sexual potency. In contrast, none of the eight patients whose penile pressures decreased had recurrence of erectile capability. Six of these patients had end-to-end aortobifemoral grafts, and concurrent external iliac disease prevented retrograde flow to the internal iliac vessels.