Atherosclerotic lesions can be detected by several methods, such as angiography, B-mode ultrasonography, computed tomography and magnetic resonance. Radioisotopic techniques, recently introduced by using radiolabelled platelets and LDL (low-density lipoproteins), can give more informations about the "metabolic activity" of atherosclerotic lesions. The aim of this study was to detect atherosclerotic lesions in 7 hyperlipemic patients using autologous apo-B containing lipoproteins labelled with 131I in order to evaluate different functional patterns of these lesions. Carotid and femoral accumulations of this radiocompound were detected in the majority of patients. The method appears promising for evaluating the "in vivo" relationships between lipoproteins, which are involved in the pathogenesis of atherosclerosis, and the vessel wall.