The effects of ginseng on the penetration of glucose into Saccharomyces cerevisiae were studied by determining the amount of glucose in the supernatant of the glucose broth medium in which some dose of water extracts of ginseng or saponin were added and the yeast was cultured for 1 hour. 1. In the 1 hour culture with 0.04%, 0.08%, 0.16%, 0.32% and 0.64% dry ginseng glucose broth medium, the penetration rate of glucose into yeast was increased 4.76%, 7.96%, 10.09%, 9.08% and 7.48% respectively. 2. In the 1 hour culture with 10^-6%, 10^-5%, 10^-4%, 10^-3%, and 10^-2% of saponin glucose broth medium, the penetration rate of glucose into yeast was increased 3.05%, 6.57%, 5.595, 4.44%. and 2.87% respectively. 3. Since the highest increasing percentage of penetration of ginseng and saponin were 10.19% and 5.89% respectively, the increasing rate of the ginseng was about twice that of the saponin. Therefore it could be concluded that the saponin contained in ginseng and other unkown components of ginseng affect the cell permeability.