Twenty-two patients with chronic empyema thoracis underwent decortication. In 11 of them, simple decortication achieved sufficient reexpansion of the lung. In the other 11 patients, our new method was indicated because the pleural space was not closed completely by simple decortication. In our procedure, the parietal wall is collapsed, without rib resection, to contact the surface of the decorticated lung. All 11 patients had a one-stage cure. Two of these 11 patients had bronchopleural fistula. The preoperative and postoperative percentage of vital capacity, percentage of forced expiratory volume in 1 second, arterial oxygen tension, alveolar-arterial oxygen pressure difference, and xenon 133 radiospirometry revealed that pulmonary function was well preserved in patients treated by our method as well as in those undergoing simple decortication. The alveolar-arterial oxygen pressure difference during oxygen inhalation improved significantly (p less than 0.05) after operation compared with the preoperative values in both groups. From the pulmonary function studies, we conclude that our method achieves results comparable with those of simple decortication for the treatment of chronic empyema thoracis. Our procedure is indicated in patients for whom it is thought simple decortication will not lead to primary cure of empyema.