Patients with familial hypercholesterolaemia have a significantly elevated risk of coronary heart disease. Accordingly, it is of crucial importance to diagnose and treat these patients before they contract premature coronary heart disease. At present, however, only a small proportion of familial hypercholesterolaemia patients are treated adequately. One main reason for this is probably the relatively vague clinical diagnostic criteria applied. We therefore advocate instead the use of molecular genetics to obtain a specific diagnosis by identifying the underlying genetic defect.