Digital subtraction angiography (DSA) with intravenous contrast injection was performed on 500 consecutive adult patients and evaluated for image quality of the carotid artery bifurcations. Diagnostic quality examinations were obtained in 974 common, 925 internal, and 904 external carotid artery segments. Sixty-two patients had standard carotid arteriography around the same time as DSA. Agreement of standard arteriograms with diagnostic quality DSA examinations was noted in 97 of 98 common, 94 of 95 internal, and 79 of 91 external carotid artery segments. All cases of complete carotid occlusion (14 of 14) were correctly interpreted by DSA. To identify a population with clinically significant stenosis, a 60% or greater reduction in diameter of the internal carotid was defined as a positive examination. Applying this criterion, the sensitivity, specificity, and accuracy of DSA as compared with standard arteriography was about 94%.