A PROTOCOL FOR the treatment of selected intracavernous and proximal internal carotid artery aneurysms is described. Intraoperative angiography is used together with intraoperative balloon occlusion of the internal carotid artery and electroencephalography to optimize the timing of an extracranial-intracranial bypass before occlusion of the carotid artery and to provide intraoperative documentation of graft patency. This protocol has been used successfully in seven patients with complex aneurysms that were unsuitable for other endovascular methods or a direct microsurgical approach. Six aneurysms were located in the cavernous sinus, and one was located on the supraclinoid portion of the internal carotid artery. There were no permanent complications; one patient had a brief episode of dysphasia, which resolved without sequelae.