Three cases of myelodysplastic syndrome (MDS) associated with BOOP-like pulmonary disease were reported. They were diagnosed from transbronchial biopsies and clinical features. In two cases, chest radiographs showed ground glass opacities or air space consolidation in both lung fields, and air space consolidation in the right lower lobe in the other case. BALF showed a marked increase of lymphocytes in one case, and organizing pneumonia and alveolitis, and alveolar spaces filled with foamy macrophages were identified histologically. Although no steroid therapy was employed, all three cases improved. However, one patient suffered a relapse 6 months later and thereafter did not respond to corticosteroid therapy.