A 57-year-old woman was admitted to our hospital because of severe dyspnea due to pulmonary hemorrhage and rapidly progressive renal failure. The patient was positive for perinuclear pattern anti-neutrophil cytoplasmic antibody (p-ANCA) and was manifested with gastrointestinal bleeding and brain hemorrhage. Thus, she was diagnosed as having microscopic polyangiitis (MPA). Laboratory examination demonstrated severe thrombocytopenia, increased prothrombin time and a high concentration of fibrin degradation products. In addition, the elevated plasma levels of D-dimer, thrombin-antithrombin complex and plasmin-plasmin inhibitor complex led us to make a diagnosis of disseminated intravascular coagulation (DIC). Complication of DIC was considered to have caused further deterioration in bleeding tendency due to MPA in the present case. The patient was treated with plasma exchange, hemodialysis, administration of corticosteroid including pulse therapy and cyclophosphamide. Continuous infusion of gabexate mesilate proved effective for improvement of systemic bleeding tendency. However, she finally died of severe infectious diseases. In conclusion, it is suggested that ANCA-associated vasculitis could be accompanied by DIC and gabexate mesilate may be a useful therapeutic agent for these disorders.