We describe a case of severe community-acquired adenovirus pneumonia in an immunocompetent 66-year-old man. He presented with one-day history of malaise, fever and emesis. Initial laboratory tests showed increased C-reactive protein level, normal white blood cell count and mild anaemia. The chest X-ray was unremarkable. A few days following admission his condition deteriorated to respiratory failure and sepsis. Chest CT-images showed bilateral infiltrates and pleural effusion. Pleural fluid and tracheal aspirates were positive for adenovirus by polymerase chain reaction assay. No other microbial pathogens were identified.