The effects of 0.5 and 1.0 MAC end-tidal concentrations of sevo-flurane on intracranial pressure, cerebral metabolic rate for oxygen, cerebral blood flow, and the electroencephalogram were compared to those of equi-MAC concentrations of isoflurane in rabbits anesthetized with morphine-nitrous oxide. At 1.0 MAC end-tidal level, both sevoflurane and isoflurane caused a significant reduction in cerebral metabolic rate for oxygen of about 50%. Neither anesthetic caused a significant change in global cerebral blood flow or cortical cerebral blood flow during either 0.5 or 1.0 MAC administration. However, both sevoflurane and isoflurane caused small but significant increases in intracranial pressure during 0.5 MAC and 1.0 MAC administration. The electroencephalogram of animals anesthetized with 1.0 MAC of either anesthetic demonstrated a burst suppression pattern with no evidence of spike or seizure activity. The data suggest that the effects of sevofluranc on cerebral blood flow, cerebral metabolic rate for oxygen, intracranial pressure, and the electroencephalogram are indistinguishable from those of equivalent concentrations of isoflurane in the rabbit.