Objectives: We aimed to evaluate antioxidant paraoxonase-1 (PON-1) activity together with malondialdehyde(MDA) (an oxidative stress parameter) levels in patientswith epilepsy.Materials and methods: Forty-five epilepsy patientswere included in the study and compared with healthycontrols (n = 45). The levels of serum MDA and PON-1activities were measured by the Ohkawa method and theEckerson method, respectively.Results: Serum MDA level was significantly higher (P =0.015), whereas PON-1 activity was sigificantly lower (P =0.011) in the patient group than the controls.Conclusions: Increased reactive oxygen species levelsin epilepsy may result in a oxidative stress, which in turncould result in decreased antioxidant PON-1 activity andincreased MDA levels.Key words: Epilepsy, oxidative stress, malondialdehyde,paraoxonase-1