We1recently reported that 40% of 100 patients more than 50 years of age studied at necropsy had at least one major extracranial arterial channel to the brain whose lumen was reduced by more than 50%, and that 11 of these patients had one or more occlusions. Whether the patients had a history of cerebral ischemia was not considered when the specimens were studied at necropsy. However, 24 of the 100 patients had a history suggesting that at some time cerebral ischemia had occurred. The present study attempts to determine the probable causal relationship between the cervical arterial lesions and the symptoms and to indicate the frequency of significant cervical arterial atherosclerotic lesions without symptoms of cerebral ischemia. This material relates to a necropsy study of atherosclerotic stenosis of the extracranial arteries supplying the cerebral circulation. The arteries studied were obtained at necropsy from the embalmed bodies of these