Since the introduction of computed thoracic tomography (CT), the implications of this imaging modality for the evaluation of patients with diverse respiratory diseases have been obvious. The particular relevance of chest CT to the diagnosis, staging, and therapy of patients with lung cancer has been readily apparent, and CT has become an established component of their noninvasive evaluation. Rapid progress in scanning technology has paralleled and complemented similar advances in bronchoscopy: as the diagnostic and interventional roles of bronchoscopy have expanded, the accurate radiologic delineation of endobronchial abnormalities and their relationships to extrabronchial structures have assumed greater importance.