A prospective study was carried out comparing two techniques of segmental arterial pressure measurements of the leg to detect, localize and quantify regional arterial occlusive disease. The measurement of pressures of the proximal and distal parts of the thigh with the narrow cuff technique permitted correct anatomic localization of aortoiliac, femoropopliteal or combined disease in 78 per cent of diseased extremities, including all limbs with isolated aortoiliac or femoropopliteal disease. A single wide cuff arterial pressure measurement of the thigh correctly localized arterial obstructions in only 19 per cent of diseased extremities. Although a wide cuff is associated with less artifactual elevation in measured arterial pressure at the thigh, this advantage is outweighed by the limitation of diagnostic accuracy in localizing segmental arterial occlusive disease. We recommend that segmental arterial pressure measurements of the limb be made at four levels on the lower extremity, including arterial pressures of the proximal and distal parts of the thigh to achieve maximal diagnostic accuracy.