We have experienced 27 cases of primary medistinal tumors and cyst from April, 1986 to April 1996. At Masan Samsung General Hospital. The results of the anslysed were as follows 1. Of 27 medistinal tumors and c,pests, 9 patients were male and 18 patients were female(m : f= 1 : 2) 2. The most common chief complaint was chest discomfort or pain(8 cases 30 %) and 17 patients(63%) were asymptomatic. 3. The most common primary medistinal tumor was Neurogenic tumor in 9 cases(33 %) followed by Thymoma in 7 cases(26 %), teratoma in 6 cases(22 %) 4. The incidence of malignancy of all case was 3 cases(11 %), all cases were symptomatic and the most common malignancy was malig. thymoma(3 cases,43 %) 5. The anterior mediastinum was the most common tumor location with 15 cases(56 %) followed by posterior 11(41 %) and middle mediastinum 1(4 %). Anterior mediastinum tumors were predominantly thymomas and teratoma and posterior mediastinal tumors were neurogenic tumors 6. Complete removal of tumor was achieved in 26 cases(96 %) and open biopsy was done on 1 case 7. Postoperative complications were continued lumbar shunt drainage in 1 case and wound infection in 1 case 8. There was no case of postoperative mortality and good clinical course in surgically completely rejected