Metabolic syndrome, a cluster of risk factors that enhances the risk for atherosclerotic cardiovascular disease, has received increasing attention in recent years, especially as the worldwide prevalence of obesity has become better defined. Recent controversy has questioned the scientific basis for metabolic syndrome, but does not negate its value as a description of a common phenotype of patients encountered in clinical practice. Revised and refined diagnostic criteria may be useful for physicians. While more research is needed to understand the pathology of the metabolic syndrome, there is no ambiguity that physicians should treat cardiovascular risk factors in individuals with metabolic syndrome.