The γ-glutamyl transpeptidase (γ-GTP) isozime specifically appears both in sera from the patients with hepatocellular carcinoma and in hepatoma tissues. The isozyme was purified from hemogenates of human hepatoma tissues by chromatography on columns of Sephadex G-200, Concanavalin A-sepharose and DEAE-cellulose. Although the enzyme did not bind to the Concanavalin A-column, after treatment with neuraminidase it became to bind to the column. The results suggest that the sugar portion of isozyme, especially the content of sialic acid, differes from of other γ-GTP isozymes.