Individuals with insulin resistance are at increased risk of glucose intolerance, dyslipidaemia and essential hypertension. In 1988, it was proposed that this cluster of abnormalities associated with insulin resistance identifies individuals at increased risk for cardiovascular disease. Recently, in an effort to raise awareness of this problem, both the World Health Organisation (WHO) and the Adult Treatment Panel III (ATP III) of the National Cholesterol Education Program have suggested a set of clinical criteria to diagnose individuals with what they both refer to as the metabolic syndrome. Although using the same term, the two groups have different goals for creating this diagnosis and different criteria to identify individuals, which relate to their different institutional goals. This review critically evaluates the similarities and differences between the two groups' concepts of the metabolic syndrome and questions the clinical utility of making the diagnosis with either set of definitions.