Internal carotid artery occlusion is the cause of carotid territory transient ischemic attacks or infarction approximately in 15% of patients. Extracranial-Intracranial (EC-IC) Bypass Study and Carotid Occlusion Surgery Study (COSS) failed to show a benefit of EC-IC bypass over medical therapy in patients with symptomatic carotid artery occlusion. Weak sides of COSS were investigators reliance on post hoc analysis, use of specific thresholds in the definition of impaired cerebral hemodynamics and high perioperative morbidity. In selected subset of patients with medically refractory ischemic symptoms, EC-IC bypass, can provide benefit from surgery performed with sufficiently low perioperative morbidity. The potential of functional and cognitive improvement after cerebral revascularization needs further investigation.