Authors retrospectively analyzed the CT findings of 102 cases of histologically proven bronchogenic carcinoma during last 4 years from January 1980 to July 1984 at Kosin Medical College. The results were as follows: 1. The sex ratio was 86 males to 16 females and the greatest number (66.7%) of cases were seen in fourth and fifth decades. 2. The distribution of histologic types of primary lung cancer as follows: Squamous cell carcinoma 66 cases, Adenocarcinoma 10 cases, Small cel carcinoma 7 cases, Large cell carcinoma 5 cases, Bronchioloalveolar cell carcinoma 1 case, Unclassified 13 cases. 3. Location of primary lesions as follows; Right lung 61 cases, Left lung 40 cases. In both lungs, the greatest number of cases were found in the upper lobes. Ratio between central and peripheral mass was 2.5:1, except adenocarcinoma (6:4). 4. CT findings were as follows: Hilar or central mass (75 cases), Peripheral mass(26), Bronchial abnormalities such as narrowing, obstruction, or displa ement (60), Thickening of the posterior wall of the right upper lobe bronchus, brochus intermedius, or left main bronchus (17), Post-obstructive changes; Atelectasis, Pneumonitis, Emphysema (34, 17, 1 respectively), Hilar adenopathy (21), mediastinal lymph node enlargement (50), Mediatinal invasion (51), Pericardial thickening (5), SVC syndrome with collateral vessels (3), Pleural effusion (27), Pleural thickening or invasion (14), Chest wall invasion (2), Distant metastasis (26). 5. In most of patients (92 cases). the size of mass was above 3cm, but in 9 cases below 3 cm. Margins of the masses were serrated or lobulated in most cases. In 5 cases, cavitary formations were noted, walls of which were thick and irregular, and air-fluid level was noted in 1 case. In 2 cases, eccentric calcification were noted within mass. 6. Among 51 cases of whom direct mediastinal invasion was suspected, 8 cases were operated upon, and this revealed that the masses were not resectable. Among the patien s in whom no direct mediastinal invasion was suggested, 12 cases were operated upon, and this revealed that the masses were resectable in all cases. 7. Staging was as follows: Stage I, 2 cases, Stage II, 13 cases, Stage III, 86 cases.