The effects of ginseng extracts on carbon dioxide generation, alcohol fermentation, and yeast cell production by Saccharomyces cerevisiae were investigated. The results are as follows. 1) In the process of fermentation, CO2 generation by yeast is faster in ginseng extracts media of 0.3%, 0. l% than in control. As the concentration of the extracts increases by 0.7% and 1.5%, CO2 generation is decreased. Among all these concentrations, CO2 generation is fastest in 0.3% of the extracts. 2) In the process of fermentation, the production of alcohol is larger in the order of 0.3%, 0.7% and 0.1% than in the control and least in 1.5%. 3) The number of yeast cell rapidly increased from 12 hours to 18 hours after cultivation and conspicuously increased in the order of 0.3%, 0.7%, 0.1%, control and 1.5%. 4) Dried yeast cell weight increased more in all the above concentration than control and among these it increased visibly in 0.3% of the extracts.