Using a vertical slab electrophoretic apparatus loaded with polyacrylamide stage gel plate, we observed a total of II bands of gamma-glutamyl transferase (EC 2.3.2.2,GGT) on a gel plate and designated these GGT I-XI by order of distance beginning at the positive pole. Positive GGT II was found in 81 (90%) of 90 cases of primary hepatic carcinoma (PHC), in 9(90%) of 10 cases of secondary hepatic carcinoma (SHC), and in only 4 (3.1%) of a total of 128 cases of acute and chronic liver disease. There was one case with positive GGT II among 45 cases of cancer of ampulla of Vater, but the possibility of hepatic metastasis could not be excluded. No GGT II was found in a total of 250 healthy persons and 21 pregnant women. PHC patients with negative alpha-fetoprotein (AFP) had a positive GGT II rate of 84.6%, whereas in those with negative GGT II the positive rate for AFP was only 44.4%.