A 5-year-old boy was admitted to our hospital with the complaint of swelling of his whole body. Urine analysis revealed nephrotic range proteinuria and microscopic hematuria. He was normotensive. Complement C3 and C4 levels were normal. Antinuclear antibodies (ANA) were negative. A percutaneous renal biopsy was performed because of the persistent proteinuria despite a full course of 4 weeks of steroid treatment. The renal biopsy was consistent with IgA nephropathy. Then cyclophosphamide was added to the treatment. Proteinuria disappeared after 12 weeks of cyclophosphamide treatment. This case of IgA nephropathy is reported because of the early age of onset and because of presenting with nephrotic syndrome.