Since the start of a school screening program by the government in 1974 for the detection of urinary abnormalities, all Japanese children between the ages of 6 and 15 years have been screened every year. IgA nephropathy has been the most common primary glomerulonephritis in children in Japan. This paper will review the clinical and pathological features of 258 children with IgA nephropathy studied at our renal units. It is hoped that this review provides the nephrologist with useful information concerning childhood IgA nephropathy.