To minimize the adverse effects of high-dose administration of steroids and cyclophosphamide in patients with myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA), granulocytapheresis (GCAP) or leukocytapheresis (LCAP) was performed to reduce inflammation. Four patients with rapidly progressive glomerulonephritis (RPGN) and one patient with pulmonary hemorrhage due to MPO-ANCA-associated vasculitis were treated by cytapheresis. The prednisolone (PSL) dose was 0.28 +/- 0.15 mg/kg/day (mean +/- SD) (range 0.18-0.50 g/kg/day). In the 4 RPGN patients, the peak serum creatinine level was 3.7 +/- 1.9 mg/dl (range 1.7 to 5.6 mg/dl). GCAP was performed in 3 RPGN patients and in 1 pulmonary hemorrhage patient. LCAP was performed in 1 RPGN patient. In the 4 RPGN patients, renal function improved after combined therapy with cytapheresis and corticosteroids. In the pulmonary hemorrhage patient, evidence of pulmonary hemorrhage on chest computed tomography scanning diminished after combined therapy with cytapheresis and corticosteroids. Cytapheresis, when combined with a low-dose or intermediate-dose PSL regimen, is effective in the treatment of ANCA-associated vasculitis.