Abstract： Objective To explore the manifestations of chest multi-slice spiral CT in patients with initial infection of swine-origin influenza A (H1N1) virus (S-OIV). Methods The chest multi-slices spirals CT images of 19 firstly diagnosed patients with swine-origin influenza A (H1N1) in our institution were retrospectively studied. CT manifestations were evaluated by three experienced radiologists. Location, appearance of lung abnormalities, abnormal distribution, pleural effusion and others (pericadiaum, lymphadenopathy and pleural thickening) were observed and quantitatively analyzed. The correlation of ground-glass and consolidation CT scores with the fever time was studied. Results The abnormal CT findings were observed bilaterally in 18 of 19 subjects including ground-glass (n= 3), consolidation (n=3 ), consolidation accompanied with ground-glass (n=12). Most of these lesions were distributed diffusively (n=14) while the others located in the middle and low lobes (n= 4). Unilateral (n=3) or bilateral (n=2) pleural effusion were observed. Lymphadenopathy (n=2), effusion of pericadium (n=1), pleural thickening (n=1) and cardiac enlargement (n=2) were also found in patients with H1N1. CT scores of ground-glass were 4. 25(n=2),3.75 (n=1),2.25(n=1),1.75(n=1),1.00(n=6),0.75(n=2), 0.50(n=2),0(n=4).CT scores of consolidation were4.25(n=1),4.00(n=1),3.75 (n=1), 2.75(n=1),1.25(n=3),1.00(n=2),0.75(n=2),0.50(n=1),0.25(n=3),0(n=4). CT scores of ground-glass were significantly correlated with the fever time (r= 0.776, P < 0.01), CT scores of consolidation had no correlation with the fever time(r=0.322,P > 0.01). Conclusions The most common CT findings in patients with S-OIV infection are diffuse distribution of bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. The increasing of ground-glass's range could be the marker of progression of H1N1 pulmonary infection at initial stage.