The metabolic syndrome has become one of the major public-health challenges worldwide. The ultimate importance of metabolic syndrome is that it helps identify individuals at high risk for both type 2 diabetes and cardiovascular disease (CVD). Several expert groups have attempted to propose diagnostic criteria for the metabolic syndrome. The most widely accepted of these have been proposed by the World Health Organization (WHO), the European Group for the Study of Insulin Resistance (EGIR), National Cholesterol Education Program- Third Adult Treatment Panel (NCEP ATP III), American Association of Clinical Endocrinologists (AACE), and recently American Heart Association-National Heart Lung and Blood Institute (AHA/NHLBI). All groups agree on the critical components of the metabolic syndrome: obesity, insulin resistance, dyslipidemia and hypertension. However, the existence of multiple definitions for the metabolic syndrome has caused confusion and has also proved difficult to make direct comparisons between the studies where different definitions were used to identify the syndrome or the data from different countries. Therefore, International Diabetes Federation (IDF) developed a new practical definition that would be useful in any country or study for the identification of people at high risk of CVD and diabetes. The metabolic syndrome requires much more studies before its definition is confirmed to acquire more accurate predictive power.