Pulmonary function tests were studied in 105 patients with cirrhosis of the liver who had no clinical or radiographical evidence of cardiopulmonary disease. Spirometric data such as VC, FRC, RV, TLC, RV/TLC and FEV1.0% were within normal limits in all subjects. However, flow-volume curve and closing volume curve were abnormal in the majority. In flow-volume curve, V25, was decreased and the V50/V25 value was increased; on the other hand, closing volume was markedly increased and FRC-CC value was reduced in the patients with hepatic cirrhosis. The closing capacity tended to exceed the FRC in the patients with arterial hypoxemia, indicating the presence of airway closure and gas trapping during resting ventilation. Therefore, ventilation-perfusion imbalance may be an important cause of arterial hypoxemia in patients with cirrhosis of the liver.