ANCA-positive microscopic polyangiitis is a rare in children. We reported an 11-year-old girl without respiratory symptoms with sever anemia which shows signs of hemolytic anemia in test data. Chest X-ray and computed tomography scans suggested alveolar hemorrhage. The patent developed night hypoxia and moderate proteinuria. Serum MPO-antibody was highly positive and renal biopsy demonstrated segmental necrosis or crescent formation. A diagnosis of microscopic polyangiitis was made. She responded to pulsed methylprednisolon and pulsed Endoxan therapy. Microscopic polyangitiis should be considered early in the differential diagnosis of patients presenting with anemia of an unknown origin.