We performed 880 pulmonary resections from January 1982 to June 1988 using Sweet's procedure for closure of the bronchial stump, in which 39 patients (4.4%) developed bronchial fistulas. Bronchoscopic studies showed that bronchopleural fistulas were located mainly at the corner of the stump. This indicates that the corner is the point with the highest tension when Sweet's procedure is employed. In some cases, stumps were injured by suture materials, resulting in bronchopleural fistulas. Since July 1988, bronchial stumps have been closed by using two pairs of teflon pledgets with additional interrupted sutures. From July 1988 to April 1990, 288 patients were treated by this new method, and only one of them developed bronchopleural fistula. This new method prevents injury of the stump by suture material and reduces the tension at the bronchial stump for a long time. Thus, pulmonary resections can be safely employed even after anti-cancer chemotherapy and/or radiation therapy.