Intrathoracic cyst was considered rare entity but one of the important diseases in the field of thoracic surgery. Authors had experienced 17 cases of intrathoracic cysts that were treated in the department of thoracic and cardiovascular surgery of Pusan NationalUniversity Hospital for 10years from January, 1983. to December,1992. The summary is as follows: Their age distribution was from 2 years and 9 months to 59 years of age, mean age 27.2 years. There were 8 males and 9 females. The type of intrathoracic cyst was 10 cases of Bronchogenic cyst, 2 cases of Pericardial cyst and 4 cases of Non specific cyst. The anatomical locations of intrathoracic cysts were 6 cases of anterior mediastinum, 2 cases of middle mediastinum, 3 cases of posterior mediastinum and 6 cases of lung parenchyme. The most common symptom was coughing and followed by general weakness, fatigue, chest pain & discomfort and hemoptysis and 6 patients were asyptomatic. The successful complete removal was done at all cases.Postoperative complications were developed in 5 patients but there was no case of hospital mortality.