Three hundred and thirty one carotid endarterectomies were performed on 279 patients during a period of twenty years from 1965 to 1984. The indication for surgery was transient ischemic attack in 67.4%, stroke in 22.7% and asymptomatic carotid stenosis in 10.0% of the operations. The overall major cerebral complication rate attending the operation was 9.6%. During the last four years' period from 1981 to 1984 the procedure morbidity was 3.6% and there was no mortality. Postoperative complications comprised 31 ipsilateral strokes and one contralateral stroke; the complications occurred during the first 24 hours in 28 cases and on the fourth or fifth day in four cases. Of these patients 11 succumbed to internal carotid thrombosis, one to cerebral infarction without thrombosis and one to intracerebral hemorrhage. The associated factors for major complications were analyzed retrospectively in the light of 32 parameters. Patients of advanced age, patients with type II diabetes mellitus, elevated serum triglycerides, high-grade stenosis or occlusion of the contralateral carotid artery, negative smoking history and those undergoing a second operation proved to be at high risk of early postoperative cerebral complications. These complications can be reduced by intraoperative use of heparin, preoperative ASA treatment and a short clamping time. Also peroperative use of shunt is obviously of benefit.