The existence of podocalyxin (PCX) in urine sediments of 30 children with IgA nephropathy was identified by positive findings of immunofluorescence testing using a monoclonal antibody (PHM-5). Three structures (cells (podocytes), casts, granules) were stained and arbitrarily scored according to their numbers and intensity of fluorescence. The urinary scores for podocytes and casts were higher in the acute stage than in the chronic stage (p < 0.02 and p < 0.01, respectively). Protein excretion and hematuria showed a strong parallel correlation in the podocytes (p < 0.005 and p < 0.001), and in the casts (p < 0.001 and p < 0.005) in the urine sediments. The urinary scores for podocytes and casts were significantly higher in cases with extracapillary lesions (p < 0.003 and p < 0.01) and with interstitial lesions (p < 0.02 and p < 0.008) but no correlation existed with the intensity of mesangial proliferation. The urinary scores for podocytes and casts were also higher in cases with mesangiocapillary IgA deposits (p < 0.04 and p < 0.04) and C 3 deposits (p < 0.03 and p < 0.04). These findings suggest that PCX in the urine sediments indicate the degree of the glomerular epithelial cell injury and is useful for clinical evaluations.