Background: It remains unknown whether the hypertriglyceridemic waist (HW) phenotype, an appropriate screening tool in adults, can also be used to screen for metabolic abnormalities in adolescents. Objective: We aimed to evaluate metabolic risk factors identified by the HW phenotype in adolescents. Design: Anthropometric and biochemical measurements were assessed in a population-based cross-sectional study of 1413 male and 1623 female Iranian adolescents aged 10 -19 y. The HW phenotype was defined as serum triacylglycerol concentrations ͧ110 mg/dL and concurrent waist circumference ͧ90th percentile for age and sex. Elevated fasting glucose (ͧ110 mg/dL), high LDL (ͧ130 mg/ dL) and low HDL (ͨ40 mg/dL) cholesterol, hypercholesterolemia (total cholesterol ͧ200 mg/dL), and hypertension (systolic or diastolic blood pressure ͧ 95th percentile for age, sex, and height) were considered as risk factors. Results: Adolescents with the HW phenotype had significantly higher prevalences of all metabolic risk factors except elevated fasting glucose than did those without the HW phenotype. After control for potential confounding variables, adolescents with the HW phenotype were significantly more likely to have high LDL cholesterol (odds ratio: 1.8; 95% CI: 1.3, 2.7), low HDL cholesterol (1.6; 1.3, 2.0), hypercholesterolemia (2.9; 2.0, 4.2), and ͧ1 (1.4; 1.1, 1.7) and ͧ2 (2.2; 1.6, 3.0) risk factors than were those without the HW phenotype. The HW phenotype had a significantly higher percentage of correct prediction of metabolic abnormalities than did overweight, elevated triacylglycerol concentration, or enlarged waist circumference. Conclusion: This study shows a clustering of metabolic abnormalities in adolescents with the HW phenotype and suggests this phenotype as a simple marker for identifying adolescents at risk of metabolic syndrome and other metabolic abnormalities.Am J Clin Nutr 2006;83:36 -46.