Antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis requires prompt diagnosis and treatment, since renal function at the time of diagnosis is significantly associated with renal outcomes. Here, we report two pediatric patients with ANCA-positive glomerulonephritis initially presenting with hematuria, mild proteinuria, and normal renal function. The first patient with a high myeloperoxidase-ANCA titer (>134 IU/mL) was diagnosed with rapidly progressive glomerulonephritis based on renal biopsy and treated with immunosuppressive therapy after 10 months of follow-up. The second patient with a low myeloperoxidase-ANCA titer (11 IU/mL) maintained normal kidney function without medication. Two cases showed different clinical course according to ANCA titer.