For the purpose of evaluation of clinical characteristics and histopathological properties in mediastinal tumors and cysts, 50 patients with mediastinal tumors and cysts treated at the department of thoracic and cardiovascular surgery in Chosun University Hospital during the period from January, 1978 to Mach, 1990 were reviewed. The results of this cases analysis were as follows; 1. of all 50 mediastinal tumors and cysts, 27 patients were male and 23 patients were female. There was no sex preference. The age distribution was from 10 months to 84 years, and mean age was 37 years old, and no age preference. 2. Subjective symptoms were as follows : Dyspnea[54%], Chest pain[44%], Coughing [34%] Fever[16%] and General malaise[12%]. Objective signs were as follows: Decreased breathing sound[46%], Pleural effusion and hemothorax[32%], Palpable neck mass[24%] and SVC syndrome[14%]. But, there were no definitive symptoms in 5 cases[10%]. 3. The most frequently encountered tumors were teratodermoid tumors[26%] followed by lymphomas[22%], thymomas[12%] and benign cysts[8%] in decreasing order of frequency. 4. Based on the subdivision of the mediastinum, 44% of the tumors were in the anterior mediastinum, 24% in the middle mediastinum, 18% in the superior mediastinum and 14% in the posterior mediastinum. 5. The malignant tumors were 25 cases[50%]. 6. The successful removal was possible in all the benign mediastinal tumors and cysts. In malignant cases, the surgical removal had been 12 cases and inoperable cases were treated to radiation and chemotherapy. 7. Postoperative complications were bleeding, wound infection, pneumothorax and vocal cord paralysis. The recurrence was 3 cases. 8. The most frequent mediastinal tumor in the west is neurogenic tumor but is teratoma in Korea.