Objective To study the early X-ray and CT findings of patients with severe acute respiratory syndrome (SARS). Methods Chest radiography and CT were performed in 28 patients with SARS within one to three days after onset of the disease. CT examinations included conventional spiral CT and high-resolution CT (HRCT). The radiographic and CT findings of these patients were analyzed retrospectively. Results Abnormal CT findings were noted in all the patients, but abnormal chest radiographic findings in 17 cases (60.7%, 17/28). CT showed single small focal patchy opacities in 23 patients (82.1%, 23/28), including oval ground-glass opacities in 20 patients, lobular distribution ground-glass opacities in 2 and small patchy consolidation in one. Multi-focal ground-glass opacities were found in 2 patients and extensive opacities in three. In the 28 patients, a total of 31 lesions were found in the upper (7, 22.6%), middle (3, 9.7%), and lower lobes (21, 67.7%). The diameter of the lesions ranged from 20 to 35 mm. Conclusion The dominant feature of early SARS patients is focal patchy opacity in the lung, and oval small ground-glass opacities are the common morphological findings on CT.