Five patients with acute encephalopathy underwent methylprednisolone pulse (mPSL-P), hypothermia and their combination therapies (3 cases, 1 case and 1 case, respectively), with excellent outcome. Two cases with severe brain edema survived. One had severe brain damage as a sequelae. The remaining one recovered well after the combination therapy with mPSL-p and mild hypothermia, despite complete obstruction of the fourth ventricle on the first CT scan; the sequelae, hemiplegia and intelligent disturbance, was only mild. Four patients who received mPSL-P therapy within 6 hours after the onset of CNS symptoms recovered well though one was left with epilepsy. These results indicate that mPSL-P and/or hypothermia therapy will be chosen as the treatment of acute encephalopathy.