The metabolic syndrome refers to the clustering of metabolic abnormalities more frequently than would be expected by chance alone. These metabolic abnormalities are all risk factors for cardiovascular disease (CVD), and the epidemiological association between these multiple risk factors points to the possibility of a unifying underlying pathophysiology. Obesity, in particular visceral adiposity, insulin resistance, and some degree of abnormal glucose metabolism coupled with dyslipidemia and abnormal blood pressure are the hallmarks of the syndrome. Epidemiological data correlates the presence of the metabolic syndrome with a proinflammatory state and greater risk for diabetes and CVD. There is also emerging evidence that the syndrome is associated with an increased risk of several malignancies. Since obesity is an increasing global burden, it is expected that the number of individuals with the metabolic syndrome will increase worldwide. An internationally accepted definition of the syndrome would facilitate both clinical diagnosis and future research to accurately assess risk and to identify preventative and therapeutic strategies.