Investigation of catamnesis of 100 patients with atherosclerotic carotid artery stenosis (50 were operated and 50--non-operated) revealed, that in some cases carotid endarterectomy prevented repeated cerebrovascular disorders and had prophylactic significance. The frequency of repeated stroke in the group of non-operated patients was 3 times higher than in the group of operated patients. In operated cases no more TIAS were observed, but they persisted in non-operated cases.