We report the case of a 46-year-old patient with liver transplantation who developed an acute respiratory distress syndrome (ARDS). The commonly associated clinical disorders, those associated with direct injury to the lung and those that cause indirect lung injury in the setting of a systemic process, were not responsible for the clinical picture. Finally, because of progressive clinical deterioration, an open-lung biopsy was performed and revealed a bronchiolitis obliterans with organizing pneumonia (BOOP). Physicians should be aware of this rare aetiology of ARDS.