The study was carried out on 25 whole carotid arteries explanted from a corpse and perfused at constant pressure to reproduce the conditions of an in vivo examination as much as possible. Out of 5 samples with intimal thickening detected by echo, fibrosis of the tunica media was observed by the pathologist in 4 and microcalcification in 1. In 4 vessels with soft plaques at echo scanning, a wide necrotic area (2 cases), slack connective tissue (1 case) and cystic lesions (1 case) were observed. Hard lesions with (5 cases) or without (2 cases) a cone of shadow at echo evaluation corresponded to fibrous (2 cases) or fibrocalcific (3 cases) plaques. The histological study of the two echo-diagnosed thrombi showed an intermediate echographic pattern and the main feature of the non-occluding thrombus was the absence of a lumen-lesion interface. Mixed plaques were diagnosed at echo in 9 arteries and the correspondent histological aspect was a typical atheromatous lesion in all cases. Thus, the comparison of the ultrasound image with the histological findings proved the reliability of echography in the detection of atheromatous lesions with an excellent agreement between the results at the 2 examinations. Since the type of carotid lesions has an impact upon clinical events these results might support the use of vascular ultrasound images in clinical applications.