The purpose of this study was to evaluate the penile vascular function by color Doppler ultrasonography (CDU) in patients with Peyronie's disease. A total of 136 men with Peyronie's disease were stratified according to their potency by history as Group I consisting of potent patients and Group II consisting of patients with erectile dysfunction. They were all evaluated by penile CDU. Overall, 70.6% had erectile dysfunction by history. CDU revealed penile vascular abnormalities in 76.5%. In Group I, veno-occlusive dysfunction (VOD) was observed in 40% while mixed (arterial + venous) vascular disease was diagnosed in 10%. Penile vascular disease was detected in 87.5% patients in Group II (ie VOD in 28%, arterial disease in 9.3% and mixed vascular disease in 50%). The prevalence of arterial disease on CDU among Peyronie' patients with erectile dysfunction (59.3%) was significantly (P < 0.05) higher then it was among potent patients (10%). The prevalence of pure VOD was almost similar for patients with or without erectile dysfunction (P < 0.05). We conclude that penile vascular abnormalities can be observed in 76.5% on cases with Peyronie's disease by CDU and this ratio significantly increases to 87.5% among cases with erectile dysfunction by history. Our data also indicate that arterial disease, accounts for much of the diminished rigidity in men with Peyronie's disease.