Mediastinoscopy was positive in 219 out of 605 cases of bronchial carcinoma (36.2%). The author analyses the age, sex, location of primitive tumor, histology, distribution of positive nodes and treatment used. Data on node involvement confirms the high malignity of the oat-cell carcinoma: though one of the rarest, this form accounts for 40% of mediastinal involvements. The data also confirm the lymphatic drainage of right side tumors (4% of crossing over) and the bilateral drainage of left side tumors (37% of crossing over). The proportion of involved nodes is 73%. In the 20 cases where surgical resection was performed this proportion is 58% and the involved nodes are largely located in the lower portion of the accessible mediastinum. Survival curves are drawn according to various parameters (location, histology, treatment). Review of the literature yields some general conclusions on the operability of bronchial carcinoma. According to belgian statistics bronchial carcinoma is the leading cause of death from cancer in the male. Probable survival for patients with positive mediastinoscopy is 7.5 months, extending from 4 months in untreated cases to 12 months after radio-chemotherapy. Prognosis was best in the 16 patients who survived the immediate postoperative period.