Serum vitamin E concentrations were measured in 47 severely handicapped patients, aged from 4 to 23 years, and in 22 controls. Thirty-three of the handicapped patients with seizures were treated with phenytoin and phenobarbital; the remaining 14 patients were not treated. The serum vitamin E levels were lower in the handicapped than in controls. Among the handicapped, those treated with anticonvulsants showed much lower levels of serum vitamin E than those untreated. Ten patients under anticonvulsant therapy were selected to receive d-1-alpha tocopherol acetate, 100 mg/day, based on their low serum vitamin E levels (range of 0.27 to 0.61 mg/100 ml). After one month of tocopherol treatment, both their serum vitamin E levels and hemolysis tests returned to normal. During a three-month tocopherol treatment period, both the frequencies of seizure attacks and the electroencephalogram (EEG) patterns remained unchanged. Supplementation with vitamin E is recommended in some patients under anticonvulsant therapy.