Mediastinoscopy is a surgical endoscopic technique used mainly for examination and biopsy of lesions of the superior and posterior middle mediastinum. It is particularly concerned with diseases that primarily or secondary involve the paratracheal and parabronchial lymphatics. A total of 18 cases of mediastinoscopy are presented with a detailed analysis of indications and results. Of these mediastinoscopy was positive in i0 [56%] and negative in 8 [44%]. The 10 positive mediastinoscopies were diagnostic in 4 patients with malignant lymphoma, 5 patients with carcinoma of the lung, one patient with active pulmonary tuberculosis. Of 8 negative mediastinoscopies, one was inoperable due to recurrent laryngeal nerve involvement, 7 patients were subjected to radical resection. Complications of mediastinoscopy were developed in 2 cases, one was minimal degree of subcutaneous emphysema on anterior chest wall, and the other was widening of right mediastinal border due to hematoma . Two complications were completely absorbed after 7 days.[KTCS 1977;2:349-354]