In 30 patients with histologically proven bronchogenic carcinoma. computed tomographic (CT) scans of the pulmonary hila, plain radiographs, and medical records were reviewed. All had abnormal plain radiographs. The CT findings included (a) a local alteration in hilar contour. (b) thickening of the posterior wall of the right upper lobe bronchus, bronchus intermedius, or left main bronchus: and (c) narrowing, displacement, or obstruction of bronchi. In 24 patients having fiberoptic bronchoscopy. CT findings of bronchial abnormality correlated closely with bronchoscopic findings. In two patients, CT showed a bronchial abnormality invisible at bronchoscopy, leading to a positive biopsy. In one patient, a bronchial abnormality invisible at CT was visible at bronchoscopy and positive on biopsy.