The waist-to-height ratio (WHtR) is a potentially more reliable anthropometric index, particularly for populations of lower height. Performance of the WHtR versus body mass index (BMI) and enlarged waist circumference (WC) in the assessment of the metabolic syndrome was tested in nonobese males and females in a high-risk Italian population. WHtR, BMI, and WC were determined in 552 males and 552 females, together with the evaluation of associated metabolic syndrome variables (hypertension, hyperglycemia, hypertriglyceridemia, and low high-density lipoprotein cholesterol [HDL-C]). WHtR > or = 0.5, the most frequently suggested threshold value, when added to any two nonanthropometric variables, gave a sensitivity for the identification of a metabolic syndrome of, respectively, 92.0% for males and 87.4% for females. Sensitivities for elevated WC (American Heart Association [AHA] criteria) and BMI > or = 25 proved lower. Areas under the receiver operating characteristic (ROC) curves for the different anthropometric indices confirmed that a WHtR > or = 0.5 provides a satisfactory balance between sensitivity and specificity. WHtR > or = 0.5 may be the most effective anthropometric index for screening high-risk patients in the diagnosis of metabolic syndrome, with the advantage of the opportunity of direct comparisons with other populations.