Eleven patients with at least 40-50% carotid artery stenosis were given intelligence and personality tests just prior to and 6 weeks after carotid endarterectomy, a surgical procedure designed to remove arteriosclerotic blockage. When compared with 8 control patients, endarterectomy patients showed increases in Perceptual-Organization IQ, decreases in time to complete a perceptual motor task, and significant reductions in suspicion, confusion, disorientation, and other personality symptoms generally associated with senility.