We report the case of a 65-year-old man with no history of respiratory disease who came to the emergency room complaining of fever, cough, yellowish sputum and increasing dyspnea of one week's duration. Severe respiratory insufficiency was evident upon examination and a chest film showed diffuse pulmonary infiltrates. Microbiological tests were negative. Lung biopsy gave evidence consistent with diffuse alveolar damage in organizing phase. Evolution of symptoms and blood gases was good after corticosteroid treatment was begun, although pulmonary fibrosis was still evident in a follow-up radiograph.