An examination was made of high dose non-treated immunoglobulin (NTIG) therapy at an early stage of the West syndrome (WS). Six patients with cryptogenic WS who suffered attacks ranging from 15 days to 6 months (mean 70 days) and 5 patients with symptomatic WS who suffered attacks ranging from 14 days to 4 months (mean 32 days), were administered NTIG 6-10 times intravenously at 100-200 mg/kg of body weight at intervals of 2 or 3 weeks. All patients with cryptogenic WS showed complete remission in accordance with normalized electroencephalogram (EEG) without following anticonvulsants medication. Of the 5 patients with symptomatic WS one patient showed cessation of clinical seizures in agreement with EEG improvement and 2 other patients revealed transient cessation of clinical seizures with recurrence. In cases of complete remission, the energy percentage of the power spectrum for each frequency band displayed a tendency toward gradual decrease of delta wave band in correspondence with the increase of theta wave band percentage after NTIG therapy, suggesting that high dose NTIG may be useful for early treatment of cryptogenic WS and for inhibiting brain deterioration owing to epileptic encephalopathy.