Hyperlipidemia is a major risk factor for atherosclerosis. Early signs of cardiovascular disease can be detected also in asymptomatic patients with hyperlipidemia. Forty-four patients with serum cholesterol greater than 300 mg/dl (7.8 mmol/l) and/or serum triglycerides greater than 500 mg/dl (5.6 mmol/l) and 35 healthy controls had their carotid and iliac arteries examined by echo-Doppler with spectral analysis. Systolic ankle pressure was also measured. A vascular score was calculated: a 0 score was assigned to normal findings and a 1 score for each artery with abnormality at echo-Doppler or Winsor index less than 0.97. The XbaI Restriction Fragment Length Polymorphism of Apo B gene was investigated in all hyperlipidemic patients. Arterial lesions, especially those of internal carotid and iliac arteries, were more frequent (p less than 0.01) in patients with high serum lipids, compared to controls. Patients with lesions were older and had higher serum triglyceride concentrations compared to those without lesions. When divided according to serum triglycerides, patients with concentrations exceeding 200 mg/dl had higher vascular score (p less than 0.02) compared to those with serum triglycerides less than 200 mg/dl. No difference in restriction fragment length polymorphism (XbaI) of Apo B gene was demonstrated in patients with arterial lesions compared to those without lesions. Non-invasive echo-Doppler examination gives useful information on the arterial involvement of hyperlipidemic patients and its use should therefore be implemented, especially when high triglyceride concentrations are present.