Epidemiological studies have documented the association between cardiovascular disease and high blood pressure, dyslipidaemia, impaired glucose tolerance, non-insulin-dependent diabetes mellitus (NIDDM), and central obesity. In fact, several of these abnormalities, often all of them, can be identified in the very same individuals, constituting the entity of the multiple metabolic syndrome. Furthermore, many of these abnormalities seem to run in families. These findings raise important questions about the genetic epidemiology of the disease and about the molecular genetic background of the most likely common nominator of this syndrome, namely insulin resistance. Therapeutic actions must also be carefully considered to avoid the encouragement of some abnormalities while treating others.