In the present study, erythrocyte lipid peroxidation, superoxide dismutase, glutathione peroxidase and catalase activities were determined in epileptic patients receiving oxcarbazepine monotherapy for 1 year and normal controls. Glutathione peroxidase, catalase, superoxide dismutase and malondialdehyde activities were investigated in a control group (15 normal healthy adults) and a group of 13 epileptic patients, before and after 1 year of oxcarbazepine treatment. The values of glutathione peroxidase and superoxide dismutase activities were statistically significant after 1 year of therapy and pretreatment. The values of malondialdehyde, were significantly different from the normal subjects and pretreatment patients values. This study suggests that the antioxidant systems of epileptic patients receiving oxcarbazepine therapy for I year were significantly affected. (C) 2004 Prous Science. All rights reserved.