A 67-year-old woman was hospitalized for progressive dyspnea on exertion. She had undergone orthotopic liver transplantation (OLT) 15 months before admission. Posttransplant therapy consisted of tacrolimus, trimethoprim/sulfamethoxazole, and prednisone (the latter two were discontinued after 1 year). Physical examination revealed fine bibasilar crackles. High-resolution chest CT demonstrated bilateral, diffuse, interstitial infiltrates. Symptoms persisted on i.v. antibiotics and bronchoscopy was performed demonstrating patchy fibroplastic plugs within air spaces consistent with bronchiolitis obliterans organizing pneumonia (BOOP). Prednisone was initiated and the patient had an uneventful recovery. BOOP was initially described as an idiopathic disease process with clinical, radiographic, pathological, and prognostic features distinguishing it from bronchiolitis obliterans and idiopathic pulmonary fibrosis. BOOP has been recognized as a complication of lung and bone marrow transplantation, but the mechanism is unknown. We report a case of BOOP after OLT to highlight the risk in all transplant patients as well as the protective effect of posttransplant prednisone.