Metabolic syndrome is a cluster of risk factors for cardiovascular disease that affects an estimated 50 million Americans. The present article reviews the metabolic syndrome with respect to its definition, epidemiology, pathophysiology and management. A primary focus in research has been to elucidate the processes determined to cause insulin resistance, the fundamental mechanism underlying the metabolic syndrome. Namely, the incidence, component characteristics and complications of the metabolic syndrome in the island of Puerto Rico are described alongside the fact that the metabolic syndrome may be milder in Puerto Rico than in the mainland United States because it is characterized by less aggressive coronary disease and a relatively normal lipid profile. This suggests that the cardiovascular complications are more influenced by genetics and culture than diabetes mellitus and hypertension.