From July 18 to July 30, 2009, 18 out of 57 patients who presented with acute febrile respiratory illness (fever of 38� C or higher, and/or a cough or shortness of breath) (8) , were confirmed with the pandemic H1N1 2009 influenza virus infection in a tertiary military hospital in South Korea. We retrospectively reviewed the medical charts, as well as the laboratory and radiologic findings of these patients.