The increasing accuracy of duplex scanning and the morbidity linked to angiography have led some authors to discard the latter when exploring patients with severe carotid lesions. In order to fully define the respective information obtained by these two explorations and to determine their impact on therapeutic decisions, were examined the file of 122 patients. The comparative analysis of preoperative color duplex scanning and angiographic results, the latter used as a reference, showed a sensitivity of 97% and a specificity of 57%, concerning the ability to detect a significant carotid artery stenosis. On the other hand, color duplex scan and angiography had the same accuracy to screen the presence of an ulceration, but could only detect two third of the ulcerations observed on pathologic examination of 94 surgically-treated patients. At last, angiography was more reliable in detecting a carotid excess of length (p < 0.001), in the identification of internal carotid thrombosis and of dissection on dysplasic arteries. In conclusion, we propose a selective indication of angiography in case of suspicion of proximal periaortic arterial lesions, of complications on dysplastic arteries, of detection of pre-thrombotic carotid lesions and in order to confirm the existence of significant stenosis in asymptomatic patients.