Aneurysmal subarachnoid hemorrhage (SAH) is a common cause of cardiopulmonary arrest (CPA). The outcomes of SAH patients presenting with CPA are extremely poor, and long-term survivors have occasionally been reported, but the circumstances under which SAH-CPA patients achieve long-term survival are unclear. Neurosurgeons will have to determine whether a SAH-CPA patient is brain-dead or not more often after enactment of the revised Organ Transplantation Act. Prediction of survival length may be important not only to neurosurgeons, but also to the transplantation team. A retrospective study was conducted to elucidate how often brainstem function was recovered in resuscitated SAH-CPA patients and whether the recovery was associated with longer survival. Among 315 patients with non-traumatic SAH admitted to our institution during 6 years, 35 (11%) presented with CPA. Ventricular fibrillation (VF) as initial cardiac rhythm was rare, observed only in 1 patient. The survival length ranged from 1 to 15 days (mean 3.5 ± 0.7 days), and none achieved long-term survival. Return of brainstem function, represented by spontaneous respiration and/or reactive pupils, was observed in 6 patients (17%), but was only partial and transient. Cardiac arrest to return of spontaneous circulation interval tended to be shorter in patients with transient recovery of the brainstem function than in those without recovery. However, the survival length was not significantly different between the two groups. In addition to the 35 SAH-CPA patients, another 44 SAH patients lost both brainstem reflexes and spontaneous respiration within 72 hours of admission. As a result, 79 (25%) of the 315 SAH patients were considered to have sustained fatal, irreversible brain damage. Review of previous experience suggests that SAH-CPA patients may survive only if the cause of cardiac arrest is VF and not brainstem damage/respiratory arrest. Approximately one-third of resuscitated SAH-CPA patients may die within 24 hours of arrival, for whom the declaration of brain death may be difficult.