Objective:To investigate the rol e of CT scanning in diagnosing severe acute respiratory syndrome(SARS). Methods: One hundred and twelve times of spiral CT scanning, 106 t imes on the chest with standard pulmonary and mediastinal window, 5 on the brain and once on the abdomen, were performed in 82 patients (37 males and 45 females ) of SARS. Results: Bilateral shadows showed in 66 patients (80.48%) and unil ateral shadow in 16 (19.52%). The lung CT findings were sub pleural focal con solidation in 26 patients (31.70%), flaky cloudy opacity in 53 (64.63%), large a rea consolidation in 9 (10.97%), ground glass blurry shadow in 31 (37.80%), a lveolar substantive shadow in 14 (17.07%) and interstitial changes in 16 (19.51% ). The pulmonary CT signs of SARS were relatively characterized by: (1) The lesi ons tending to multiply occur, mostly to be bilaterally distributed and commonly involved in the lower lung field. (2) The lung shadows mostly showed as sub pleural focal consolidation, flaky cloudy shadow, large area consolidation, grou nd glass blurry shadow, and often accompanied with signs of broncho inflat ion. (3) Having opacified nodular shadows in the alveolar cavities. (4) Rapid pr ogressions or changes on the size, amount, and distribution of the lesions likel y to be found in dynamic observation of chest X ray and CT scanning, i.e., ma rkedly dynamic changes found within 24 to 48 hrs. Lesions with these characteris tics may be recognized as pulmonary changes possibly induced by SARS. Complicati ons were found in 6 patients (7.31%), including tuberculosis of lung and brain a ccompanied with pneumomediastinum in one patient, secondary infection of lung in 2, pneumothorax in 1, pulmonary fungus in 1, and pyothorax in 1.Conclusion: CT scanning is a sensitive method for diagnosis of SAR S, by which more accurate assessment of the abnormal changes of lung and occurre nce of complications in SARS patients can be made. Objective: To investigate the rol e of CT scanning in diagnosing severe acute respiratory syndrome (SARS). Methods: One hundred and twelve times of spiral CT scanning, 106 tmes on the chest with standard pulmonary and mediastinal window, 5 on the brain and once on the abdomen, were performed in 82 patients (37 males and 45 females) of SARS. Results: Bilateral shadows showed in 66 patients (80.48%) and unil ateral shadow in 16 (19.52%). focal con solidation in 26 patients (31.70%), flaky cloudy opacity in 53 (64.63%), large a rea ​​consolidation in 9 (10.97%), ground glass blurry shadow in 31 17.07%) and interstitial changes in 16 (19.51%). The pulmonary CT signs of SARS Was quite characterized by: (1) The lesi ons tending to multiply occur, mostly to be bilaterally distributed and commonly involved in the lower lung field. ( 2) The lung shadows mostly showed as sub pleural focal consolidation, fla (3) Having opacified nodular shadows in the alveolar cavities. (4) Rapid pr ogressions or changes on the size, amount, and distribution of the lesions likel y to be found in dynamic observation of chest X ray and CT scanning, ie, ma rkedly dynamic changes found within 24 to 48 hrs. Lesions with these characterisics may be recognized as pulmonary changes possibly induced by SARS. Complicati ons were found in 6 patients (7.31%), including tuberculosis of lung and brain a ccompanied with pneumomediastinum in one patient, secondary infection of lung in 2, pneumothorax in 1, pulmonary fungus in 1, and pyothorax in 1. Conlusion: CT scanning is a sensitive method for diagnosis of SAR S, by which more accurate assessment of the abnormal changes of lung and occurre nce of complications in SARS patients can be made.