Immunological mechanisms have been implicated in the pathogenesis of epileptic seizures in some patients and in experimental animal models of epilepsy. A beneficial effect of high dose intravenous gammaglobulin (IVIG) has been demonstrated for some children with intractable epilepsy. In this study we treated 9 children ages 1.1-9.2 years (mean 5.0 years) with intractable epilepsy not responsive to conventional antiepileptic drugs (AEDs) and steroid therapy. Eight children had Lennox-Gastaut syndrome and 1 had complex partial seizures with secondary generalization. Each child received 3 doses of IVIG (200 mg/kg of polyvalent immunoglobulin) on Days 1, 15 and 36. Concomitant AEDs were not changed. Four children had complete remission, 3 had partial response with a more than 50% reduction in seizure frequency and 2 had no response. Onset of response varied from immediate to 7 months after the last injection. No toxicity was noted. Duration of remission was 9 months in 1 case. The other 3 cases have remained in remission to date with a follow up period of 22-26 months. We conclude that IVIG is a safe therapy which appears to be effective in some children with intractable seizures. Children with shorter duration of their seizure disorder (< 1 year) and relatively preserved cognitive function (IQ > 70) appear to have a more favorable response. Larger scale controlled trials are needed to determine the optimal timing and dosage, as well as to identify specific subgroups which may benefit most from IVIG treatment.