The quality of the anastomosed vessels berore vascular grafting has been shown to influence long-term patency rates in arterial reconstructive procedures. A study was designed to assess vascular graft quality during microvascular artery bypass procedures for impotence, correlate identified vasculopathy with the clinical history and gain insight into vascular pathophysiological mechanisms. A total of 194 donor or recipient vessel segments was biopsied m 111 patients with impotence who underwent microvascular artery bypass surgery during a 10-year period. A prospective histological grading system was used m a blinded randomized fashion. A preexisting vascular pathological condition was identified m 48% of the patients. Proliferative lesions above the internal elastic lamina with luminal stenosis were identified in 38 of 69 dorsal penile artery segments (55%) and 8 of 69 inferior epigastric artery segments (12%). Venous hypertrophy or sclerosis was observed in 13 of 56 deep dorsal vein segments (23%). Systemic atherosclerosis was likely the underlying pathophysiology of vascular disease in the inferior epigastric artery. Vasculopathy in the deep dorsal vein and the dorsal penile artery segments was probably related to the consequences of blunt trauma to the pelvis, perineum or penis, which was considered to occur following direct vessel wall injury with immediate or delayed vascular disease or indirect vessel wall injury secondary to proximal arterial occlusion and delayed distal vascular disease. Future studies are needed to investigate the relationship between preexisting graft vasculopathy in microvascular artery bypass surgery for impotence and long-term clinical success rates.