Objective: To explore the imaging features of sever pneumonia caused by avian influenza subtype H5N1 virus in adults,and to evaluate the long-term follow-up characteristics.Methods: Five patients(3male,2 female,median age :31years)with clinically diagnosed H5N1 human avian influenza from 2006 to 2015 were selected,the clinical and imaging features,X-ray and CT semi-quantitative score were retrospectively analyzed.Results: For these five patients,three recovered and two died,one patient followed-up for 5 years.Imaging manifestations: five cases appeared ground-glass opacity or patchy consolidation in a segmental or lobular lung,and involved bilateral pulmonary promptly,the rapidly developed into consolidation and ground-glass opacity in both lungs,even extensively confluent consolidation; three cases showed consolidation and interstitial fibrosis in recovery phase,then mainly showed interstitial fibrosis and bronchodilation in later recovery phase and after recovery.Chest X-ray and CT scored 6~9 and 9~15 during 4~6 days; then chest X-ray scored more than 16 during 7-12 days,in which it scored 22~24 for two died patients.After 12 days,four cases complicated with infection,2 case with merger pneumothorax,chest X-ray scored 16~20.Two cases were respectively followed up for one year and five years,corresponding CT scored 1and 3.After 5 years follow-up,HRCT still showed fibrous stripes,mist ground-glass opacity,alveolate,beadlike and twisted bronchiectasia,mediastinal and subpleural emphysema in one case.Conclusion: Imaging score can directly reflect the dynamic state of severe pneumonia caused by avian influenza subtype H5N1virus and help evaluate state of illness,remaining lesions in long-term follow-up is probably associated with the degree of irreversible damage in lung.