Preoperative determination of the extent of bronchogenic carcinoma at presentation was assessed by CT using a 4th generation scanner with a 3-second scan time in 98 patients whose disease was later surgically staged. Prospective CT interpretations correctly staged 33 of 35 (94%) resectable lesions, and disease in 41 of 45 (91%) patients who had lesions that were not resectable for cure. No definite opinion was rendered on the scans of the remaining 18 patients. Retrospectively analysis using slightly modified criteria resulted in a correct prediction of resectability in 28 of 30 (93%) patients (scans showed a normal mediastinum with no lymph node larger than 1 cm in diameter), and nonresectability for cure in 34 of 34 (100%) patients (scans showed either direct extension of the primary neoplasm into the mediastinum or mediastinal lymph-node enlargement greater than 2 cm in diameter). However, scans of 34 of 98 (35%) patients showed inconclusive findings (mediastinal lymph-nodes with 1-cm to 2-cm diameters, neoplasms abutting but not definitely invading the mediastinum, pleural or pericardial thickening, or additional noncalcified nodules).