Background: Population-based studies for prevalence of metabolic syndrome (M.S) in children and adolescents are relatively rare. The aim of this study was to assess the Prevalence of M. S and correlated factors among children and adolescents aged 10 to 19 years in Ahvaz.Methods: In this descriptive-analytical population- based study, 2246 children and adolescents, 10-19 years old (1113 male and 1133 female) in Ahvaz, were evaluated. Anthropometry, biochemical measurement and blood pressure (BP) were assessed. Modified ATP III criteria 2005 were used for M.S. definition. Center for disease and Control preventions (CDC) percentile were applied to define cut off points of waist circumference and BP.Results: Prevalence of M.S. was 9% (95% CI: 8-10%) with prevalence in male 11% (95% CI: 10-12%) and female 7% (95% CI 6-8%). Among individuals with M.S, triglyceride (TG) and decreased high density lipoprotein (HDL) cholesterol levels were the most common components (33.5% and 24.1%, respectively). Prevalence of M.S was higher in overweight persons comparing to participants with at risk and normal weight group (in male: 24.1%, 14.3% and 9.9% respectively P = 0.0001), (in female: 22.6%, 18.3% and 4.5% respectively P = 0.0001). Among the correlated factors of M.S age (P = 0.0006), sex and BMI (P = 0.0001) had significant differences between subjects with and without M.S. whereas there was no significant difference between two groups in ethnicity, history of breast fed, birth weight neonatal ICU admission, maternal history(GDM, gestational HTN, Parity) and family history of HTN, obesity and DM (P > 0.05).Conclusion: This study shows high prevalence of M.S in Children and Adolescents in south west of Iran (Ahvaz) especially in overweight persons.