The prevalence and severity of extracoronary atherosclerosis in 728 patients (572 men and 156 women; average age 59 years) referred for coronary angiography and who had a history of coronary disease for at least 2 years, were assessed by ultrasonography. This population was divided into 3 groups: Group I, 115 patients without lesions at coronary angiography: Group II, 76 patients with mild coronary stenosis ang Group III, 537 patients with at least one severe coronary artery stenosis, a group which included 294 cases of single vessel disease. The authors observed a strong correlation between the presence, severity and diffusion of the coronary artery disease and ultra sonographic signs of peripheral arterial disease: the frequency increased regularly from 45% in Group I to 88% in patients with triple vessel disease in Group III. About two thirds of patients in Group III had carotid or lower limb atherosclerosis and half of them had atherosclerosis or aneurysm of the abdominal aorta. Severe peripheral lesions were not common but all the aortic aneurysms were observed in Group III. Similarly, simultaneous disease in all three peripheral arterial territories ranged from 12% in Group I to 51% in Group III. The risk of finding peripheral arterial disease was increased in patients with coronary artery disease compared with normal subjects. For each peripheral localisation, the risk was two-fold in cases of mild coronary disease and three or four-fold in patients with triple vessel disease in whom the risk of finding at least one severe peripheral lesion was multiplied by ten. The authors conclude that the prevalence and severity of ultrasonographic peripheral atherosclerosis in documented coronary patients was closely related to the presence, severity and diffusion of the coronary lesions.