Antineutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis usually shows histopathologic features of pauciimmune crescentic glomerulonephritis and occurs late in life. We report a 14-year-old Japanese girl presenting with proteinuria, hematuria and mildly elevated serum creatinine. A renal biopsy specimen demonstrated crescentic glomerulonephritis, immunofluorescence showed mesangial IgA staining. Electron microscopic examination disclosed paramesangial deposits. Serum ANCA against myeloperoxidase (MPO) were detected at high titers. Myeloperoxidase-ANCA-related nephritis accompanied by IgA nephropathy is considered rare in childhood and teen years. Yet, if ANCA assays and detailed electron microscopic examination of renal specimens were performed routinely in patients with rapidly progressive glomerulonephritis, the diagnosis might be more frequent in young patients.