In 1994, the Health Council of the Netherlands published a report entitled 'Genetic screening' which contained 12 criteria for genetic screening programmes. However, the list does not prioritize the various criteria. From the list we have selected two criteria that we consider to be the most important. Firstly, the genetic screening test should be able to discriminate between subjects who are likely to develop the disease and those who are not. Secondly, there should be an effective treatment for subjects with the genetic defect. From this point of view, for example, screening for the C282Y mutation is not a suitable approach for detecting primary haemochromatosis. Although 85-90% of the patients with this disease are homozygous for this mutation, the majority of the carriers will not develop the disease. The 12 criteria of the Health Council of the Netherlands are still applicable. However, when taking a decision as to whether or not genetic screening is useful, we recommend that priority be given to the two primary criteria.