The computed tomography of thorax has had considerably less impact in patients managment than that of head andabdomen, because the conventional chest radiography is a much more sensitive and accurate exmaination than theplain films studies of the head and abdomen. It has progressively been identified that the CT of chest is superiorto the conventional radiography in detection of small pulmonary nodules including occult metastatic lesions, inevaluation of character of hilar enlargement, and in staging of known bronchogenic cancer. And especially inmediastinum, the CT is superior to the any other conventional radiography in outlining lesions and determiningcharacter and extent of lesions. At the department of radiology, Kyung Hee University Hospital, 87 cases of CT ofchest were performed with EMI-CT 5005 whole-body scanner from Oct. 1977 to Aug. 1979. The results were as follows;1. The fifty eight cases of considred to be pathologic findings were 23 pleural thickening and/or effusion, 14bronchogenic carcinoma, 8 inflammatory lesions of lung parenchyme, 6 mediastinal lesions, 3 metastatic lesions, 3COPD, 1 trauma, respectively. 2. No gravity-dependent change was noted in patients with chronic obstructivepulmonary disease (COPD), which was frequently seen in normal subjects. Diminished numbers of pulmonary vesselswas noted in COPD. 3. Small nodules in lung, retrosternal, posterior costophrenic and subpleural regions, whichwere not found on conventional radiograph, can be detected by chest CT. 4. Differentiation of dilated centralpulmonary artery from pulmonary mass in enlarged hilum and determination of adjacent mediastinal invasion,manifested by obliterated fat plane, was possible. 5. The cases of mediastinal widening such as paraspinallipomatosis, pericardial fat pad, teratoma, and bronchogenic cyst were easily determined by means measuring theattenuation coefficiencies. 6. Small amount of pleural and pericardial effusion as easily detected.