Influenza pneumonia and influenza-associated severe exacerbation of pre-existing heart and lung disease are responsible for major complications that may require intensive care unit admission. Here, we report the case of a diabetic 70 year-old man hospitalised in the intensive care unit (ICU) of the University Medical Center of Reims (France) for a severe bilateral and alveolar pneumonia requiring mechanical ventilation. This patient had received a classical antibiotic treatment by amoxycillin (3 g/24 hours per os); 48 hours later, he was admitted in ICU for a respiratory failure that evolved rapidly towards an acute respiratory distress syndrome. Because of the context of a winter influenza outbreak, a nasal swabbing sample was tested for the presence of Influenzavirus nucleocapsid-antigens (Immunochromatographic test; BinaxNow Flu A & B, Binax, Portland, USA). This rapid assay revealed the presence of an Influenzavirus A respiratory infection five days after the beginning of the respiratory syndrome. This rapid viral diagnosis will be further confirmed in post mortem by the positive Influenza strain isolation onto lung tissues by classical cell culture techniques (Influenzavirus A strain, H3N2). Influenza pneumonia is a significant cause of morbidity and mortality, especially during influenza epidemics. The use of commercially available rapid diagnostic tests for influenza associated pneumonia, allows the potential use of new specific anti-neuraminidase drugs, which can be efficient during the 30 hours after the beginning of the clinical influenza syndrome.