The presence of both N- and O-linked carbohydrate was demonstrated on gamma-glutamyltransferase (GT) from human liver and kidney. The N-linked carbohydrate constituted 25-30% of the total molecular mass of the enzymes. O-Glycosylation was detected on both subunits of the liver enzyme, but only on the small subunit of the kidney enzyme. Lectin blot analysis indicated that the glycan chains were of the complex type for both the liver and the kidney GT and lectin blotting may to some extent distinguish the two enzymes.