Background and Objectives: Metabolic syndrome (MS) is associated with increased risk of cardiovascular disorders. MS is increasing among adolescents. This study was conducted to determine the prevalence of MS in 11-18 years old Birjandi school children in 2012. Materials and Methods: This cross–sectional study was conducted on 2394 eleven-eighteen years old school children in Birjand (1304 girls and 1090 boys) through Multiple-Cluster Sampling. Height, weight, waist circumference and blood pressure were measured by standard methods. Blood glucose, triglycerides, cholesterol, HDL-C and LDL-C were measured after a 12-hour fasting. MS was defined according to the modified Adult Treatment Panel III criteria. Data were analyzed by the SPSS software (ver. 16) using statistical T test, logistic regression and Chi square at P