In 34 cirrhotic patients with esophageal varices, a significant but temporary deterioration in pulmonary function tests occurred 24 h after endoscopic injection sclerotherapy using 5 % ethanolamine oleate. Included were vital capacity, forced expiratory volume in 1 s, closing volume/vital capacity and arterial oxygen content. Twenty-four hours after the sclerotherapy, the patients complaining of postinjection retrostemal pain had a larger fall in vital capacity and forced expiratory volume in 1 s than did the patients without pain. Before the injection sclerotherapy, 11 of 34 patients had an arterial hypoxemia (Pao2 less than 80 mm Hg). In these patients, there was a significantly (p < 0.001) higher value of closing volume before sclerotherapy and there were larger changes in both closing volume (p < 0.01) and arterial oxygen content (p < 0.01) 24 h after the injection sclerotherapy than in the patients without hypoxemia. Reversion to a state before sclerotherapy was attained 7 days after the sclerotherapy. Thus, patients undergoing sclerotherapy for bleeding esophageal varices should be closely monitored with regard to pulmonary function.