A case history of a 16-year-old boy with hepatocellular carcinoma and an intermediate deficiency of alpha1-antitrypsin (MZ phenotype) is presented. Previous reports have suggested that hepatocellular carcinoma may be associated with the Z variant of antitrypsin and either a severe or intermediate antitrypsin deficiency. The present case is unusual because of the rather high level of the serum trypsin inhibitory capacity for an MZ heterozygote (1.633 units), which may be due to involvement of the liver by the tumor or to a recent partial hepatectomy. PAS-positive antitrypsin globules were seen in the primary tumor and in nodules metastatic to the mesentery, as well as in nonneoplastic portions of the liver. Hepatocellular carcinoma is another disease state that may occur preferentially in individuals with either severe or intermediate deficiencies of alpha1-antitrypsin.