To clarify the prophylactic effect of epidural anesthesia with buprenorphine on postoperative pulmonary complications, the incidence of pulmonary complications after chest surgery was evaluated in 2 groups: the group that underwent epidural anesthesia, namely the test group, and the control group. Pulmonary complications were classified as follows: mild complications, sustained wheezing and/or small atelectasis-like shadows seen on chest x-rays. These improved by conventional methods except for bronchial toilet. Moderate complications included pneumonia and/or respiratory failure and/or atelectasis which needed bronchial toilet. There were 56 cases (58%) with no pulmonary complications in the control group and 89 cases (77%) in the test group. The number of patients with pulmonary complications were 40 (42%) in the control group and 27 (23%) in the test group, respectively (p less than 0.01). Those with mild or moderate complications were 25 (26%), 15 (16%) in the control group and 21 (18%), 6 (5%) in the test group, respectively. There was significant difference between no complication group and moderate complication group (p less than 0.01). These results show that epidural anesthesia is useful in preventing pulmonary complications after chest surgery.