Objectives : This study was conducted to investigate the effects of ginseng saponins and commercial surfactants such as Triton X-100, sodium deoxycholate, and sodium dodecyl sulfate on the gastric enzyme-catalyzed hydrolysis. Methods : Saponins (a surface-active plant component) from fresh ginseng root were extracted to examine its effect on the gastric enzyme-catalyzed hydrolysis. Commercial surfactants such as Triton X-100, sodium deoxycholate, and sodium dodecyl sulfate were also employed in the hydrolysis system to compare their effects with that of the ginseng saponins. The effects of surfactants on the gastric enzyme-catalyzed hydrolysis were measured by using a spectrophotometer. A spectropolarimeter was used to examine the conformational change of enzymes and substrates by the addition of ginseng saponins into the system. Results : Both the tryptic and the peptic digestion of milk casein or eggalbumin were slightly improved with an increase in the amount of ginseng saponins in the system. Triton X-100 showed an effect similar to that of ginseng saponins, while sodium dodecyl sulfate and sodium deoxycholate diminished the hydrolysis. Circular dichroism spectra of enzymes and substrates was significantly changed by the addition of ginseng saponins into the system. Conclusions : These results show that ginseng saponins affect positively the gastric enzyme-catalyzed hydrolysis, and suggest that the digestion of substrates by gastric enzymes is affected by the change of enzyme conformation by ginseng saponins.