The recent years have seen significant progress in the area of genetically determined liver diseases. For hereditary hemochromatosis, Wilson's disease and alpha-1 antitrypsin deficiency the underlying genetic defects have been described and well characterized. Although a direct relationship between genetic defect and disease manifestation exists genetic test only have a limited diagnostic usefulness which requires exact knowledge of the underlying molecular pathology. The classical C282Y and H63D mutations of the HFE gene only show a penetrance of 10-20% in hemochromatosis and are not useful for population screening. Genetic screening for ATP7B (Wilson's disease) and alpha-1 antitrypsin deficiency variants is limited by the existence of a plethora of individual mutations. Genetic tests are mainly restricted to the counseling of families in whom these diseases are present. Foremost the diagnosis of the three diseases is reached by clinical, biochemical and in some instances also histological means which are supplemented and confirmed by the use of appropriate genetic tests.