Pulmonary cysts occupy an important place among diseases of the chest. and their treatment has to be considered by taking into account the pathologic condition of each disease. We have reported here the findings obtained through clinical experience of 6 cases of intrapulmonary bronchial cyst, 36 cases of giant bulla, and 127 cases of spontaneous pneumothorax, who were operated on during the past-odd 10 years at this hospital, with regard to the concept, pathologic condition, developmental mechanism, clinical symptoms, diagnosis and treatment of each disease.