Among the 257 pediatric patients examined, 104 were classified as having drug-resistant epilepsy (DRE). In all of them genetic, metabolic, chromosomal and infectious causes were investigated, and brain imaging with computed tomography scans and nuclear magnetic resonance were obtained. Since treatment with gammaglobulins (GGs) has been reported to be useful in pediatric cases of epilepsy, informed consent for GGs treatment was obtained in 43 patients with DRE. The etiology or evidence of brain lesions was identified in 16 of them. In 31 of these patients, neither conventional drug treatment, nor a trial with adrenocorticotropic hormone was successful. Intact monomeric GGs, 400 mg/kg, were given intravenously. A second dose was given after 15 days and, thereafter, every 21 days for a maximum of ten injections (protocol A), or every 2nd day for a maximum of five doses (protocol B). In every patient, the type of epilepsy was identified according to the classification of the International League Against Epilepsy. The frequency of seizures was recorded for a period beginning at least 6 months before the administration of GGs. Immunological evaluation was also performed before and after the treatment with GGs. A transient decrease of the seizure frequency was noted in 12 subjects. In another patient with infantile idiopathic myoclonic epilepsy, seizures disappeared for 30 months. In 1 case a persistent 80% reduction in the number of seizures was observed. A persistent disappearance of seizures was noted in a subject with complex partial seizures (CPS) that followed an idiopathic infantile spasm syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)