Graves' disease is one of the common autoimmune diseases, and it has been controlled by such antithyroid drugs as propylthiouracil (PTU) or methimazole. There are a number of side effects, including agranulocytosis, skin rash, hepatotoxicity, fever, arthralgia and a lupus-like syndrome during treatment. PTU has been recently observed to be associated with the development of antineutrophil cytoplasmic antibody (ANCA) positive vasculitis, and this can cause diffuse alveolar hemorrhage. A 32-year-old woman with Graves' disease had been treated with PTU for 4 years, and she had experienced intermittent hemoptysis for 2 weeks before she visited the hospital. Both myeloperoxidase and proteinase 3 ANCA were positive without other organ systems being involved. She was diagnosed with PTU-induced vasculitis. Cessation of PTU and administration of corticosteroids improved the clinical manifestations.