Propylthiouracil(PUT) is a drug which used at Grave's disease. But PTU has recently been observed to associated with antineutrophil cytoplasmic antibody(ANCA)-positive vasculitis resulting in, infrequently, diffuse alveolar hemorrhage. We report the case of a patient who developed diffuse pulmonary hemorrhage after she had been taking PTU for two years. She had received a diagnosis of Grave's disease at two years ago. The serologic study was positive for ANCA with myeloperoxidase(MPO) specificity. Bronchoalveloar lavage(BAL) fluid analysis revealed hemosiderin- laden macrophages. Such findings suggested propylthiouracil-induced dffuse pulmonary hemorrhage associated with antineutrophil cytoplasmic antibody. To our knowledge, this represents the first documentation in a case of PTU-induced diffuse pulmonary hemorrhage in Korea.