Staging is the quantitative assessment of malignant disease and allows logical groupings of patients with a similar extent of disease for prognostic, therapeutic, and analytic purposes. In bronchogenic carcinoma a stage is assigned based on size, location, and the extent of invasion of the primary tumor, as well as the presence of any regional or metastatic disease. Selecting the most appropriate treatment for a patient with bronchogenic carcinoma depends on precise staging. The extent of local invasion and presence of metastatic disease will determine the likelihood of complete resection and possible cure. Careful assessment of the history, blood chemistry, radiographic studies, bronchoscopy, mediastinoscopy, and exploration (thoracotomy) are all important staging tools. Routine radionuclide scans have no useful role when there is no clinical or laboratory evidence of metastases. The T status of a tumor is best judged by bronchoscopy and at thoracotomy. Thoracic surgeons must be familiar with the techniques available to determine T status intraoperatively and use this information when planning resection. Computed tomography of the chest has fallen short in predicting direct invasion of the mediastinum and chest wall. Cervical and anterior mediastinoscopy remain important tools in determining operability. Intraoperative assessment of node involvement determines the extent of resection and likelihood of cure.