Novel γ‐glutamyl transpeptidase (γ‐GTP) was purified from ascites or sera obtained from hepatoma patients by means of following procedures including ammonium sulfate fractionation, separation by 2 cycles of preparative polyacrylamide disc electrophoresis and elimination by a technique of immuno‐absorption using affinity chromatography. The purified γ‐GTP was shown to be homogeneous as judged by disc electrophoresis. Some physicochemical properties of the partially purified enzyme obtained at the stage of 2 cycles of preparative disc electrophoresis such as heat stability, pH optimum. Km value for substrate and effect of some cations are reported.