The aim was to compare the Adult Treatment Panel (ATP) III criteria with the International Diabetes Federation (IDF) definition of metabolic syndrome (MS) in adults with excess adiposity who were considered a high-risk population. A cross-sectional study was carried out in 274 adults with excess adiposity. MS was assessed in all volunteers considering the ATP III criteria and the new IDF definition. Among all individuals, 130 (47%) were similarly classified under the two definitions. Under the ATP III criteria, but not the IDF definition, 2 (1%) participants had MS, and 29 (11%) subjects had MS under the IDF definition but not the ATP III criteria (p=0.009). The ATP III criteria and the IDF definition were useful for identifying MS in adults with excess of adiposity; however, the IDF proposal identified a greater percentage of patients.