We report a patient who underwent two allogeneic bone marrow transplants for chronic myelogenous leukemia, initially in 1984 and again after relapse in 1990, who developed an identical pulmonary syndrome at a similar interval following each transplant. The patient presented with a non-productive cough, bilateral inspiratory crackles, and multiple patchy infiltrates on chest X-ray. Pulmonary function testing revealed a restrictive abnormality but no obstructive defects. The appearance of this pulmonary disorder after each transplant coincided with the development of chronic graft-versus-host disease. In both instances, this pulmonary syndrome completely reversed with corticosteroid therapy. The patient's chest computed tomographic scan and lung biopsy specimens were consistent with the diagnosis of bronchiolitis obliterans with organizing pneumonia (BOOP). While bronchiolitis obliterans has been reported following allogeneic transplant, BOOP has not previously been reported in this setting.