A 34-year-old woman who had been treated with propylthiouracil (PTU) for hyperthyroidism, was admitted because of bloody sputum and pyrexia. The chest CT scan showed some nodules in both lung fields. The serum level of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) was high, but proteinase-3 antineutrophil cytoplasmic antibody (PR-3 ANCA) was negative. A limited form of Wegener's granulomatosis without PR-3 ANCA was ruled out, because of the absence of abnormalities in the upper airway and kidney. No lesions other than the multiple pulmonary nodules of the lung were detected. We diagnosed MPO-ANCA associated vasculitis induced by PTU. After the termination of PTU, bloody sputum, pyrexia, and pulmonary nodules improved spontaneously and the serum level of MPO-ANCA returned to normal gradually. The case of MPO-ANCA positive vasculitis associated with multiple pulmonary nodules following propylthiouracil treatment is very rare.