Background: It has long been recognized that primary childhood nephrotic syndrome (NS) is an immunological disorder. In recent years it has been proposed that NS is a consequence of an imbalance between oxidant and antioxidant activity. Reactive oxygen metabolites play an important role in the pathophysiologic process of a surprisingly wide variety of clinical and experimental renal diseases. Objectives: The aim of the present study was to examine the activity of the main antioxidant enzymes and the total antioxidant status in children with NS. Methods: The study included three groups of children. Group I included 20 children during the proteinuric phase of nephrotic syndrome. Group II included 20 children, 6 months after remission which was induced by steroid therapy. The age range was 4-10 years, with a mean of 6.2 ± 1.4 years. Group III included 20 healthy children, matched for age and sex as a control group. Total antioxidant status (TAS), glutathione reductase (GR) and glutathione peroxidase (GPX) were measured for all. Results: TAS was significantly reduced in both group I and group II compared to the control (p=0.01). In children from Group I the activity of GR and GPX were significantly lower than in controls. In children from Group II GR activity was also significantly lower than in the control group (p=0.006), but there was no significant difference in GXP level. The activity of TAS & GXP were lower in those with first attack of NS (Group I) and those in remission (Group II). There was no significant difference in GR level between Children in Group I and those in Group II. The total cholesterol (TChol) and low density lipoprotein cholesterol (LDL) concentrations in Group I were significantly higher than those in Group II and in the controls. There was no significant differences in high density lipoprotein cholesterol (HDL) & triglyceride (TG) levels in the two Groups I& II. In children with first attack NS a negative correlation appeared between TAS and TChol and LDL. There was no correlation between TAS and other laboratory results. In children with remission there was a negative correlation between TChol and TAS. But no correlation between TAS and other laboratory results. Conclusions: We concluded that total antioxidant status is diminished in children with NS. Abnormal antioxidant status may be partly related to abnormalities of some antioxidant enzyme activity and high lipid concentration.