Theoccurrence of PAS-positive, diastase-resistant, inclusion bodies in hepatocytes has been used as a marker of heterozygous (Pi MZ) alpha1-antitrypsin deficiency in order to study the frequency of lung, liver and malignant disease in a consecutive autopsy material from a well defined population. Typical PAS-positive inclusion bodies were found in the liver in 26 (3.7%) of the 700 cases studied. In these 26 subjects both liver (cirrhosis or fibrosis) and lung disease (emphysema) were significantly more prevalent (p less than 0.001) than among PAS-negative controls. The prevalence of malignant disease did not differ between the groups. The results are consistent with the concept that heterozygous (Pi MZ) alpha1-antitrypsin deficiency predisposes to both liver and lung disease but does not influence the survival rate.