Many cases of drug-resistant infantile epilepsy (West syndrome, Lennox-Gastaut syndrome, Landau-Kleffner syndrome, severe myoclonic epilepsy, and Rasmussen's encephalitis) were found to respond in some measure to treatments with intravenous immunoglobulins (IVIG), but relapses were common. However, as the side effects of IVIG infusion are insignificant, it is better not to deny treatment of epileptic encephalopathies to patients who have been treated unsuccessfully even with new anti-epileptic drugs.