Objectives:Toexplore the clinical characteristics and chest imagingfeatures in children with severe influenza A (H1N1)and offer reference for its earlier diagnosis and treatment. Methods:The clinical data of 5 patients with severe influenza A(H1N1)in PICU of Chongqing children’s hospital in november 2009 were retrospectively analyzed. Results:5 cases of severe influenza A (H1N1)were all complicated with severe pneumonia and respiratory failure

among which 2 cases were complicated with acute respiratory distress syndrome (ARDS)

3 with liver function damage and myocardial damage respectively. The five severe patients were all recovered. Chest radiographic and computer tomography (CT)findings in children with severe H1N1 were characterized by unilateral or bilateral extensive exudative process

mainly in lower lobe. Conclusion:Pneumonia

respiratory failure and ARDS are important complications for severe influenza A(H1N1)and the chest extensive exudative process could be found in the early cases. It is important for the children with severe H1N1 to undergo chest X-ray or CT examination and oxygen therapy earlier.