Recently new soybean saponins with D DMP (2,5-dihydroxy-6-methyl-2,3,- dihydro-4H-pyran-4-one) moiety have been isolated from legumes. The purpose of this study is to characterize ROS scavenging activities of DDMP saponins ($alpha$g, $eta$g saponin) isolated from Glycine max (L.) Merrill. The scavenging activity on OH was examined in terms of lipid peroxidation in the rat liver homogenates and the same activity on $O_2$ was also determined in the xanthine-xanthine oxidase system, respectively. Up to 0.25 mg DDMP saponins ($alpha$g and $eta$g saponins) did not cause any significant effects on the prevention of lipid peroxidation as compared with the control group. In terms of superoxide scavenging activities, 0.25 and 0.5 mg $alpha$g saponin inhibits only 2.6% and 5.5% (p<0.05) of the control group, respectively. However, $alpha$g saponin dose-dependently (p<0.01, r=0.955) inhibits the formation of superoxide radical unto 21.3% of the control group with a maximal dose of 0.5 mg (p<0.01), equivalent to 0.17 units of superoxide dismutase activity.