Ligation of the carotid artery in the neck has become part of the surgical armamentarium for treating inaccessible or technically difficult intracranial aneurysms. Obliteration of an aneurysm by sacrificing the parent vessel has also been employed for the treatment of unclippable posterior circulation and middle cerebral artery aneurysms. Because parent vessel occlusion is not well tolerated by all individuals, the use of an extracranial-intracranial bypass has been advocated in order to improve the safety of this procedure. The purpose of this report is to detail our methods and results with the use of extracranial-intracranial bypass for the treatment of giant internal carotid and middle cerebral artery aneurysms in 35 patients and review the literature to determine the status of the use of the bypass for other intracranial aneurysms.