Sclerotic processes of glomeruli in chronic pyelonephritis (CPN) and chronic diffuse proliferative glomerulonephritis (CDPGN) were investigated in a lectin binding study in connection with an immunofluorescent examination of protease inhibitor deposition. Ulex europaeus agglutinin-I (UEA-I), which is specific to a certain terminal α-L-fucosyl residue of glycoconjugates, specifically labelled intact endothelia of glomerular capillaries, peritubular capillaries and blood vessels in human kidneys. Segmental or global loss of the UEA-I binding with glomerular capillaries was observed in the sclerotic areas where αi-antitrypsin (α1AT) deposits were always detected in the glomeruli with segmental or global sclerosis of CPN. This high correlation between loss of UEA-I binding and α1AT deposition was also observed in the affected glomeruli of CDPGN. In considering glomerular sclerosis, it is significant that loss of UEA-I binding and α1AT deposition are common to both CPN and CDPGN, although their original etiologies are quite diffe