Eighteen patients with bilateral bullae underwent simultaneous operations via median sternotomy. Each patient had giant bullae occupying at least one third of the each hemithorax and also had various degree of exertional dyspnea. All patients showed subjective as well as objective improvement and there was no mortality or morbidity. Late follow-up study for objective evaluation of this operative procedure clarified that the forced expiratory volume for one second (FEV1.0) and arterial oxygen tension (PaO2) were significantly improved after the operation, whereas the vital capacity and arterial carbon dioxide tension (PaCO2) showed no apparent changes. Serial study of cardiopulmonary hemodynamics during the bilateral thoracotomy was performed with Swan-Ganz catheter and hemodilution method. By abrupt decompression of the cyst, decreases in pulmonary arterial pressure, cardiac output, or systemic arterial pressure were noted during the bilateral thoracotomy. These hemodynamic changes were much more evident in the cases ventilated by single lumen tube than the cases operated upon using double lumen tube with separate ventilation. This operative procedure was applied on the cases with bilateral spontaneous pneumothorax and metastatic lung tumor. The clinical advantages of this bilateral operation via median sternotomy were discussed.