We have experienced 50 cases of mediastinal tumors and cysts from March, 1979 to August, 1985 at Kyung Hee University Hospital. The results of this cases analysis were as followings; 1. Of all 50 mediastinal tumors and cysts, 26 patients were male and 24 patients were female. There was no sex preference. The age distribution was from 27 months to 64 years, and mean age was 33.5 years old, and also no age preference. 2. The most common mediastinal tumor was benign cysts [12 cases], which comprise 24% of all mediastinal tumors and cysts. The second common mediastinal tumor was teratoma [9 cases-18%], and followed by thymic tumors and tuberculous granuloma [7 cases-14% each], neurogenic tumors [5 cases-10%], and other tumors [10 cases-20%]. 3. The anterior mediastinum was most common tumor location, and followed by middle, superior, and posterior. 4. All 9 teratomas were developed at anterior mediastinum, and 4 of 5 neurogenic tumors were developed at posterior mediastinum. Thymomas were developed at anterior and superior mediastinum. The bronchogenic cysts had no predilection of location. 5. The most common chief complaint at admission was chest pain or discomfort [23 cases-46%], and followed by cough with or without sputum, and exertional dyspnea. Asymptomatic patients were only 7 patients [24%]. 6. Of all 50 cases, 38 cases [76%] received radical tumor resection, 7 mediastinoscopic biopsy, 3 explo thoracotomy and biopsy, and 1 neck mass biopsy. 7. There were 2 hospital deaths, one of which was a patient who suffered malignant thymoma and Myasthenia Gravis. The patient received radical tumor excision, but died at 7th POD. The other patient was a patient with malignant transformation of the benign cystic teratoma. The operative mortality was 4%.