On the basis of our previous report on the biochemical studies of Ginseng substances, it was attempted to observe the effect of ethanol extract (WGpet-alc) and petroleum ether extract (WGpet) of White Ginseng on the activity of human serum GIDH and pure GlDH in vitro. The activity of human serum GlDH and pure GlDH was significantly increased in the presence of WGpet-alc. On the other hand, an inhibitory effect of WGpet on GlDH was. observed even at low concentration. It was also confirmed that these activating and inhibitory effects have the same pattern as the effects on albino rat hepatic GlDH.