Objective:To improve the knowledge on propythiouracil(PTU)-induced antineutrophil cytoplasmic antibody(ANCA)-associated vasculitis.Methods:6 cases of PTU-induced ANCA-associated vasculitis were analyzed on clinical manifestation,laboratory and biopsy findings,therapy and prognosis.Results:All patients with Grave's disease had been treated with PTU from 2 months to 7 years suffered from ANCA-associated vasculitis, which can also appear after withdrawal of PTU. Clinical manifestations are different with only skin, joint, muscle involvements on mild cases or lung, renal and hematological involvement on severe cases. Sera from all patients were anti MPO-ANCA positive. All patients responded to withdrawal of PTU and administration of prednisone and immuno-suppressants well with ANCA declined or turned to negative.Conclusion:PTU can induce ANCA-associated vasculitis in the part of which lung and kidney can be seriously involved. Early withdrawal of PTU and administration of immunosuppressive agents might improve the prognosis.