A 37-year-old woman had been found to have proteinuria in October 1996. About 8 months later, the first renal biopsy was performed, revealing focal segmental necrotizing and crescentic glomerulonephritis. At that time, serum creatinine was 1.0 mg/dl and urinary protein 3+. In October 1999, laboratory tests revealed positivity for MPO-ANCA and a serum creatinine level of 1.42 mg/dl, anemia and proteinuria of 2+. A second renal biopsy showed almost the same histological findings. Accordingly, a diagnosis of MPO-ANCA positive glomerulonephritis was made. This patient was thought to be a rare case of MPO-ANCA-positive slowly progressive glomerulonephritis presenting focal segmental tuft necrosis and crescents.