Abstract: Objective To explore imaging examination methods for the severe cases with pneumonia caused by H7N9 subtype human cases of avian-origin influenza virus(H7N9 virus) and the imaging features in chest X-ray and CT.Methods A retrospective ana1ysis of the relevant c1inical and imaging materials of 17 cases with pneumonia caused by H7N9 virus,whose diagnosis were confirmed by Centers for Disease Control of Guangdong and Shen-zhen.Results The imaging features of the chest X-ray and CT were: (1)Patchy ground glass opacity and pulmona-ry consolidations were observed in 17 cases and 3 cases showed lung air sac. (2)The ground glass opacity and pulmonary consolidation were mainly observed at lower lobe and dorsal lung (17/17), shown by an extensive involvement of multiple lobes and segments of both 1ungs, the lesions of 17 cases involved in 3 or more lobes, of which 16 cases involved in 4 to 6 lobes.(3) Small amount of pleural effusion were observed frequently(13/17), but much less of enlarged lymph nodes in hilar and mediastinal can be seen(1/17). (4) Rapid spreading and variations of the lesions were common, lesions spread more than 50% lung feild within 48 h in 17 advanced cases. Longer with the recovery time, patchy shadows and fibrous bundles can be seen in all these cases.Conclusion The severe cases with pneumonia caused by H7N9 virus has the clinical imaging features of early ground glass opacity and pulmonary consolidation in lungs and mainly happened at lower lobe and dorsal lung and rapid spreading and absorption of the di-sease focuses with prolongation in time.Imaging examination and diagnosis remain to be the important measures for making clinical diagnosis and treatment options,and eva1uating therapeutic effects.