Carotid bifurcation atherosclerosis was demonstrated in 34 of 108 patients with familial hypercholesterolemia and coronary artery disease by B-scan, continuous-wave Doppler sonography, and intravenous digital subtraction angiography. An intensive combined therapy of diet, colestipol, and nicotinic acid was mounted to control the hypercholesterolemia of these patients. Their serial sonographies and digital subtraction angiography were evaluated independently by technical specialists who served as coinvestigators. The data obtained suggest that extracranial arterial disease can develop concurrently with coronary artery disease in a significant proportion of patients with familial hypercholesterolemia, and amaurosis fugax, transient ischemic attack, cerebral infarction, and myocardial infarction did not recur during 58-72 months of control of familial hypercholesterolemia in this series of patients.