The purpose of this study was to investigate the relationship between obesity and, erythrocyte SOD (superoxide dismutase) activity and serum antioxidant mineral (Fe, Zn, Cu, Mn and Se) concentrations of adolescents. Subjects were assigned to one of two groups such as obese ($BMI{geq}25$, 32 boys, 24 girls) and normal group (18.5 < BMI < 23, 27 boys, 30 girls) Subjects were evaluated based on anthropometric measurements, 24-hr dietary recalls and blood analysis. The mean age of the total subjects was 13.8 years. The mean weight (p < 0.001), BMI (p < 0.001) and body fat (p < 0.001) of obese were higher than those of normal group. There was no significant difference in nutrient intake between obese and normal groups. SOD activity of obese group was not significantly different from normal groups, in both males and females. However, in the males, serum Cu concentration of obese were significantly lower than those of normal group. In the females, Serum Mn concentration of obese were significantly lower then those of normal group. In the correlation analysis, BMI of the subjects had significantly negative correlations with serum Cu, Zn and Mn. To summarize the results, increase of obesity may lead to decrease of serum antioxidant minerals such as Cu, Zn and Mn.