Mediastinoscopy as devised by Carlens is a method of exploration employing palpation, inspection and biopsy of the superior mediastinum. The procedure, which has gained wide acceptance in the specialties of otolaryngology and chest disease has proved very useful in establishing a diagnosis in the throacic disease and, espicially, in the assessment of resectability in bronchogenic pulmonary carcinoma where conventional methods are failed. Author have experienced seven cases of mediastinoscopy in National Medical Center, Korea and six hundred forty seven cases of mediastinoscopy in Aarhus University Hospital, Denmark and discussed with the literatures.