Objectives This study sought to characterize the prevalence of metabolic syndrome (MetS), its 5 components, and their pharmacological treatment in U.S. adults by sex and race/ethnicity over time. Background MetS is a constellation of clinical risk factors for cardiovascular disease, stroke, kidney disease, and type 2 diabetes mellitus. Methods Prevalence estimates were estimated in adults (≥20 years of age) from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2010 (in 2-year survey waves). The biological thresholds, defined by the 2009 Joint Scientific Statement, were: 1) waist circumference ≥102 cm (males adults) and ≥88 cm (female adults); 2) fasting plasma glucose ≥100 mg/dl; 3) blood pressure of ≧130/85 mm Hg; 4) triglycerides ≥150 mg/dl; and 5) high-density lipoprotein-cholesterol (HDL-C)