A 63 year-old gentleman with a history of mitral valve repair and recent travel to the Philippines presented to our hospital with complaints of dry cough for three days. His clinical exam was remarkable for diffuse rhonchi. Initial chest radiograph was nonrevealing. The patient clinical condition deteriorated in the emergency department (ED) with rapidly progressive respiratory insufficiency and interval development of radiographic infiltrates (Figure 1). The patient was then admitted to the intensive care unit (ICU) and broad-spectrum antibiotics started. As the patients’ symptoms and radiological findings worsened bronchoscopy and bronchoalveolar lavage were emergently performed. The later yielded no organisms. A transbronchial biopsy was non diagnostic. An open lung biopsy was performed and consistent with bronchiolitis obliterans organizing pneumonia (BOOP). Again, all cultures were negative and no organisms seen. The patient was started on intravenous corticosteroids with and excellent clinical response and two days later was extubated.