Forty-one epileptic and not hyperuricemic subjects, aged 2 to 54 years, had epileptic seizures, ranging from 1 to 220 weekly (mean = 21.3). All seizure types were represented. They were already medicated with two or three antiepileptic drugs with plasma drug concentrations maintained in therapeutic range. They were treated with allopurinol in doses ranging from 150 to 300 mg daily. After 20 to 35 days of this regimen, a progressive decrease of the weekly seizure frequency was observed in two-thirds of the cases. After a follow-up of 3 to 9 months, seizures disappeared completely (22%) or decreased more than 50% (47%). Twenty-five percent of subjects continued to have the same seizure frequency, while about 6% were worse than before.