1. Objectives The purpose of this study was to observe the anti-oxidant effects of Hyangsayangyi-tang(HY) in SD rats. 2. Methods This experiment was used the tissue of stomach, spleen and pancreas cells of 6, 52 and 68 weeks old SD rats. Each age group was again divided into three groups. One group, as normal group, was not-treated cells, another group, as control group, was saline-treated cells, and the last group, as experimental group, was HY-treated cells. After culture for 48 hours, each groups measured the level of SOD, GSH, MDA and NO in the tissue of stomach, spleen and pancreas cells. 3. Results and Conclusions The activity of SOD were significantly increased in spleen cell of 52, 68 w-HY group, pancreas cell of 68 w-HY group and in stomach cell of 52, 68 w-HY group compared with those of the normal and the control groups. The level of GSH were significantly increased in spleen cell of 52, 68w-HY group and in pancreas cell of 68w-HY group compared with those of the normal and the control groups. The level of MDA were significantly decreased in pancreas cell of 68 w-HY group compared with those of the normal and the control groups. The level of NO were significantly decreased in spleen cell of 68 w-HY group, pancreas cell of 52, 68w-HGD groups compared with those of the control groups. According to results, HY showed anti-oxidant effect. Investigation into the clinical use of the HY is suggested for future research.