Seventeen patients with at least 50% carotid artery stenosis were given intelligence and personality tests just prior to and 6 weeks after carotid endarterectomy. When compared with nine control patients, the endarterectomy patients showed increases in verbal-comprehension I.Q., perceptual-organization I.Q., decreases in time to complete perceptual motor tasks, decrease in asphasic signs, and significant reductions in anxiety, suspicion, confusion, disorientation, and other personality symptoms generally associated with senility. Statistical evaluation showed these results to be valid.