A wide variety of histologically or clinically different tumors and cysts can occur from the many anatomical structures located within the mediastinum. We report the analysis of the 26 cases of mediastinal tumors and cysts, experienced in the Department of Thoracic and Cardiovascular Surgery, College of Medicine, Hallym University from March 1983 to February 1990. Sex ratio of male to female was 1:1.16 and mean age was 33.4 years. Malignant tumors were 8 cases[30.7%], benign tumors were 18 cases[69.2%] The most common histologic types were thymoma, 6 cases[23%] and teratoma, 6 cases [23%] followed by neurogenic tumor, 4 cases[15%] and mediastinal tuberculoma, 3 cases [11.5%]. The most frequent symptoms were chest pain and discomfort. Most of benign tumors were completely removed and malignant tumors were treated with anticancer chemotherapy and radiotherapy after operation. Postoperative complications were developed in 4 cases[15.3%] and hospital mortality was 3.8%.