The surgical adjuncts of hypothermic circulatory arrest, exsanguination, and barbiturate cerebral protection were evaluated in nine cases of cerebral aneurysms felt unapproachable by conventional surgery. These techniques were used in seven posterior circulation aneurysms, two of which were giant and two giant anterior circulation aneurysms originating at the middle cerebral artery bifurcation. Four patients had excellent outcomes, two had a fair result, one had a poor result, and two died. The outcome of surgery reflected that of the management of patients with unruptured or ruptured aneurysms. Three of the four patients who did well had unruptured aneurysms, and all three of the cases in which death or a poor outcome resulted occurred in patients presenting with subarachnoid hemorrhage. The rationale for the use of hypothermic circulatory arrest is discussed, and the surgical indications, techniques, and anesthetic considerations are also reviewed.