Differences between human renal cortex and human renal cell carcinoma (RCC) in asparagine (Asn)-linked sugar chain structures of gamma-glutamyltransferase (GGT) were investigated by using a serial lectin affinity chromatographic technique. The relative amounts of GGT which passed through the concanavalin A (Con A) column but bound to the phytohaemagglutinin E column, were significantly decreased in RCC, but there were significant increases in the relative amounts of GGT which bound weakly to the Con A column and passed through the pea lectin (PSA) column, and bound strongly to the Con A column and bound to the wheat germ agglutinin column in RCC compared with those of the normal renal cortex. A significant correlation was observed in RCC between nuclear grade and relative amount of GGT which bound weakly to the Con A column and passed through the PSA column. The findings indicate that Asn-linked sugar chain structures are altered in RCC and suggest that studies of qualitative differences of sugar chain structures of GGT might lead to a useful diagnostic tool for human RCC.