ANCA (anti-neutrophil cytoplasmic antibody)-associated vasculitis is characterised by small vessel vasculitis and presence of autoantibodies, ANCA. It can be a life-threatening disease with renal/respiratory failure. Current standard therapy in induction remission for ANCA-associated vasculitis is combination of high-dose glucocorticoid and IV-cyclophosphamide. This regimen is effective (remission rate; 80-90%), but often cause various glucocorticoid-related side effects. Especially, infection is related to death. Thus a new regimen reducing glucocorticoid dose is required.