OBJECTIVE To analyze the relationship between waist circumference (WC) and metabolic syndrome (MS) related traits among middle school students in Beijing and to provide the proof for making WC cut-offs among Chinese children and adolescents. METHODS In the study, 1 427 students aged 13-18 years were investigated. The indexes included height, weight, WC, blood pressure, total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol and fasting blood glucose. The subjects were divided into three WC groups by using P(75) and P(90) of WC reference norms for Chinese children and adolescents. Obesity and MS components were assessed with the criteria of Working Group on Obesity in China and International Diabetes Federation, respectively. RESULTS HDL-cholesterol in high WC group was lower than that in low WC group, and other MS related traits showed the opposite direction. Excepting fasting glucose, female total cholesterol and triglycerides, MS related traits were different significantly within the WC groups. Excepting raised fasting blood glucose and female raised triglycerides, the prevalence of MS components increased and aggregated in high WC group significantly. The distribution of different WC groups was correlated with that of obesity groups based on body mass index criterion. CONCLUSION The P(75) and P(90) of WC reference norms could well indicate the increase of the prevalence of MS components, suggesting the increased risk for cardiovascular disease.