The metabolic syndrome represents a complex combination of the symptoms obesity, insulin resistance, dyslipoproteinemia, hypertension, and type 2 diabetes. These components have a heterogeneous genetic basis and appear to be closely linked. Obesity is determined by a polygenic constellation and produces insulin resistance, hypertension and dyslipidemia. In addition, defects in the signal transduction of insulin appear to aggravate the insulin resistance independent of obesity. Type 2 diabetes is produced by a third genetic predisposition and is precipitated by the failure of pancreatic beta-cell to compensate insulin resistance. Because prevalence and course of the diabetes markedly depend on the extent of obesity and insulin resistance, these symptoms of the metabolic syndrome represent crucial targets for preventive and therapeutic strategies.