Background: Several hypotheses have been made about the pathogenesis of vitiligo, and some of them were presenting evidence on the role of oxidative stress as an initial pathogenic event in melanocyte degradation. Objective: In this study we evaluate the role of oxidative stress in the pathogenesis of active localized vitiligo by measuring the serum levels of superoxide dismutase (SOD) enzyme, glucose-6-phosphate dehdrogenase (G-6-PD) enzyme, and malondialdehyde (MDA) and plasma levels of catalase (CAT) by spectrophotometric assay. Patients and Methods: This case control study was conducted on 20 patients with active localized vitiligo and 10 healthy participants as controls. The indicator of oxidative stress is determined by measuring serum levels of MDA. The role of antioxidant system is determined by measuring serum levels of G-6-PD, SOD and plasma levels of CAT. Results: The mean serum levels of G-6-PD, SOD and plasma levels of CAT were significantly decreased in vitiligo patients than in controls (P < 0.05 for all) while the mean serum levels of MDA was significantly increased in vitiligo patients than in controls (P