To evaluate oxidant status in children after febrile seizures, 61 children were studied: 31 with and 30 without a febrile seizure. Erythrocyte malondialdehyde, glutathione peroxidase, and superoxide dismutase levels were assessed in all patients. Erythrocyte malondialdehyde and glutathione peroxidase levels were significantly higher and superoxide dismutase levels were significantly lower in the febrile seizure group. Febrile seizures may cause significant oxidative stress, and these changes in oxidant status may be a step along the way to cell damage subsequent to febrile seizures.