Three children ranging in age from 2 to 5 years with acute disseminated encephalomyelitis (ADEM) were successfully treated with high-dose intravenous immunoglobulin (IVIG), Their symptoms were somnolence, fever, headache, vomiting, and resting tremor. In all of these patients, it was difficult to distinguish the condition from viral encephalitis before analyzing the myelin basic protein. ADEM was diagnosed because of increased levels of myelin basic protein in their cerebrospinal fluid and abnormal high-signal intensity on T-2,-weighted magnetic resonance imaging. All patients were given IVIG at a dose of 400 mg/kg/day for 5 consecutive days. The patients rapidly regained consciousness in 14 hours, 2 days; and 4 days and demonstrated a complete clinical improvement within 18 days, 10 days, and 7 days of the initiation of the treatment, respectively. IVIG may prove useful as an alternative treatment to corticosteroids for ADEM, (C) 1999 by Elsevier Science Inc. All rights reserved.