In the present study, we investigated the effects of valproic acid (VPA) on nitric oxide (NO) level, lipid peroxidation, and antioxidant enzyme activities in 21 epileptic children and 26 healthy controls. The subjects were selected from those who visited for a checkup or medical treatment at the Mustafa Kemal University Research Hospital. Serum levels of NO-2, NO-3, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were analyzed by redox or enzymatic reactions and spectrophotometry. Based on the NO-2 and NO-3 levels, the NO concentration was about 10% higher in VPA group than in the control group (p < 0.001). However, no significant difference was detected for serum MDA, SOD, and CAT levels. It is suggested that NO would play a role in the mechanism of antiepileptic effects by VPA treatment. (c) 2009 Elsevier B.V. All rights reserved.