✓Angiograms of patients who underwent carotid artery surgery were correlated with the surgical findings, cerebral blood flow measurements, and the following manifestations of cerebral ischemia: amaurosis fugax, transient cerebral ischemia,small completed infarct, generalized cerebral ischemia, and progressing stroke. The degree of carotid stenosis and presence of ulcerating plaques and soft thrombi could be predicted accurately; tiny ulcerations were not angiographically identifiable in the presence of severe stenosis. Generalized cerebral ischemia corresponded closely with severe degrees of bilateral carotid stenosis or unilateral occlusion in conjunction with contralateral stenosis. Internal carotid to middle cerebral artery slow flow was found in many patients with a progressing stroke or an unstable neurological state. Retrograde ophthalmic flow was found frequently in symptomatic patients with high-grade stenotic lesions at the origin of the internal carotid artery. Localized alterations included small vessel occlusion, retrograde collateral flow, avascular areas, focal slow flow, and reactive hyperemia and were correlated with symptoms of focal cerebral ischemia.