Propylthiouracil (PTU) is one of the most common drugs used in the treatment of Graves' disease. There are a number of side effects found with PTU use including fever, rash, arthralgia, and flu-like symptoms. Recently antineutrophil cytoplasmic antibodies (ANCA) positive vasculitis after PTU treatment was reported as a rare side effect, which can cause diffuse alveolar hemorrhage and glomerulonephritis. A 45-year-old woman with Graves' disease had been treated with PTU for five months, complained of hemoptysis due to pulmonary alveolar hemorrhage causing anemia, and also had hematuria. Simple chest X-ray and HRCT showed bilateral consolidation and bronchoalveolar lavage fluid revealed alveolar hemorrhage. A serologic test was positive for ANCA against myeloperoxidase and proteinase-3. Such findings suggested that the presence of PTU induced ANCA positive vasculitis. Cessation of PTU and the administration of high dose steroids improved the clinical manifestation, radiologic and serologic findings. We observed ANCA titer serially for 6 years. During the follow up period, ANCA titer decreased slowly and stayed within the acceptable upper normal limit.