During carotid reconstruction in 200 patients with symptomatic extracranial stenosis, four patients died, four were stabilized, and 192 were improved. The anesthetic technique used consisted of enhancement of cerebral blood flow by hypercapnia, diminution of cerebral oxygen requirements by halothane anesthesia, spontaneous respiration, and maintenance of each patient's normal blood pressure during the reconstruction. Narrowing of the carotid artery ranged from a 30% compromise on one side to a 100% compromise on one side with 75% on the other. The figures on the patients' recovery are comparable to recent reports of similar work and are superior to earlier experience with local anesthesia. Cerebral venous oxygen saturation proved to be the best guide to management; arterial carbon dioxide tension (Pco2) is an inadequate index of cerebral blood flow and oxygenation in cerebrovascular atherosclerosis. Few arrhythmias were observed during hypercapnia. It is probably desirable to maintain an optional Pco2 for good cerebral circulation in all patients.