Correlation of the anatomic and surgical features in 360 cadavers and in 260 patients operated for bronchial carcinoma reveals that the lymphatics of the lung reach the ipsilateral mediastinum, sometimes directly and sometimes by sites which do not correspond to the anatomic site of the injection or of the pulmonary lesion. This implies the need for systematic eradication of all the lymph nodes of the ipsilateral mediastinum during surgery for bronchial carcinoma. In cases of tumoral lesions (N2), the prognosis is better when only one site is involved, whether the nodal disease is microscopic, uni- or multiglandular, with or without rupture of the capsule and whatever treatment is carried out, even when resection seems macroscopically complete to the surgeon. This is explicable in the light of the anatomic study, which shows that the lymph node chain is a functional entity which channels the lymph into the systemic circulation, either at the venous confluence of the neck or into the thoracic duct in the mediastinum. When only a single chain is affected, there is a greater than 70% chance that systemic metastases are already present, 90% when N2 affects 2 chains, while in N3 cases (lymph passage to contralateral chains) the incidence reaches virtually 100%. However, macroscopically satisfactory excision allows management of the local problem, and involvement of the mediastinal nodes, even with capsular rupture, cannot be considered as a contraindication in the absence of clinically detectable systemic metastases.