Ten patients with intracranial internal carotid artery (ICA) aneurysms were managed by combining ICA ligation with an extracranial to intracranial bypass procedure. Nine of these grafts were proven patient by angiogram. One patient was unable to return for postoperative angiograms; his graft ahd appeared patent on physical examination. Seven aneurysms were intracavernous, two were giant carotid-ophthalmic aneurysms, and one aneurysm was at the intracranial bifurcation of the ICA. Despite occlusion cerebral blood flow (CBF) measurements of 20 ml/100 gm/min or less in six patients, only one patient was unable to tolerate ICA ligation. Three patients developed transient aphasia, but there were no permanent neurological deficits associated with the carotid occlusion. Seven patients had improvement in pre-existing extraocular palsies or visual field defects. Others remained stable. The combination of an extracranial to intracranial microvascular bypass procedure with ICA ligation seems to be an effective method of treatment for aneurysms near the base of the skull that cannot be obliterated by a direct intracranial approach. The addition of the bypass procedure permits ICA ligation in patients who would not otherwise have tolerated occlusion of that vessel. Intraoperative xenon CBF measurements are an important adjunct to the operation.