Thoracoscopy, mediastinoscopy and/or mediastinotomy and explo-thoracotomy were performed and confirmed diagnosis of the 26 cases of the mediastinal tumors, those were admitted and treated at the Department of Thoracic and Cardiovascular surgery, Chonbuk National University Hospital, from June,1976 to September, 1986. We experienced 7 thoracoscopies, 7 mediastinoscopies &/or mediastinotomies, and 12 explo-thoracotomies. The most common histologic type was teratoma and lymphoma [6 cases]. Of the 26 cases of the histologically confirmed mediastinal tumor, 19 were benign tumors and 7 were malignants. 19 cases of benign tumors were surgically resected with good result but one case of the surgically resected malignant thymoma was recurred 4 months later. 6 cases of malignant lymphoma and one case of recurred malignant thymoma were treated with chemo-and radiation therapy. Thoracoscopy and mediastinoscopy with tissue biopsy were simple in procedure and had a tissue diagnosis with obtaining the pathologic tissue in a acceptable complication rate and reduced exploratory thoracotomy.