We presented our experience about cognitive changes associated with vascular reconstructive surgery in patients with ischemic cerebrovascular diseases. 1) Bypass surgery improves impaired cognitive function. Further, degree of cognitive improvement is associated with degree of an increase in CMR02 and a decrease in OEF. 2) Cerebral hyperperfusion after carotid endarterectomy, even when asymptomatic, is associated with impairment of cognitive function in patients undergoing CEA. Further, development of hyperperfusion syndrome is associated with persistence of postoperative cognitive impairment.