α1-Antitrypsin deficiency predisposes to pulmonary emphysema, liver cirrhosis and hepatocellular carcinoma. Anecdotal evidence and a large autopsy study suggest that severe lung and liver disease rarely coexist in the same subject, but this has not been studied in patients. Therefore we investigated 27 patients with severe α1-deficiency (Pi ZZ) and pulmonary emphysema for signs of liver disease and impaired hepatic function. A subgroup of 7 patients underwent quantitative liver function tests. On physical examination or ultrasonography, cirrhosis or tumor was not suspected in any patient. Conventional liver function tests were completely normal in 17 patients. Elevated serum activities of n-glutamyltranspeptidase and/or aminotransferases were seen in 10 patients. In some, the elevation was only marginal and in none more than twice normal. The serum bilirubin concentration and activity of alkaline phosphatase were increased in 1 patient. Serum protein, albumin, fibrinogen, anti-thrombin III, α1-fetoprotein concentrations, serum activities of cholinesterase and glutamate dehydrogenase, activated partial thromboplastin time and prothrombin time were normal in all patients. The indocyanine green half-life was abnormal only in 1 of 6 patients, suggesting that hepatic blood flow was not impaired in the study group. However, the lidocaine half-life and galactose elimination capacity, parameters of hepatic metabolization, were impaired in 4 and 6 of 7 patients, respectively. We conclude that liver disease or impaired liver function is not a clinically relevant problem in most patients with pulmonary emphysema due to αi-antitrypsin deficiency. But results of quantitative liver function tests, although performed in only a small group of patients, suggest that hepatic metabolization might be impaired even in those patients who present with pulmonary dise