The accuracy of staging of lung cancer is reflected by the extent of mediastinal lymph node sampling. The more extensively a patient is tested, the more likely there will be the accurate N-stage diagnosed. Adequate lymph node dissection during surgery for lung cancer therefore requires complete dissection of all three ipsilateral mediastinal compartments including the infracarinal region. Additional contralateral mediastinal lymph node exploration may not be justified. A direct therapeutic effect of mediastinal lymph node removal may be attributed to the prevention of local tumor growth. However, its overall prognostic significance remains unclear because it must be assumed that proven tumor within the mediastinal lymph nodes reflects the state of tumor generalization that may not be cured by localized therapeutic means. New systemic interventions are clearly warranted to significantly improve prognosis in stage II and III lung cancer patients.