Objectives: This study was undertaken to investigate the effects of Yijin-tang and GamiYijin-tang on the gastrointestinal functions of rats Methods: Sprague-Dawley rats were used as experimental animals, and were administered Yijin-tang (Sample I group, 47.5 mg/ml) and GamiYijin-tang(Sample II group, 38.37 mg/ml, Sample ill group, 85.3 mg/ml) water extract once a day. Changes of gastric juice volume and intestinal mobility index were measured. The effects on colitis induced by dextran sulfate sodium in the rats were also observed. Results: 1. Gastric juice volume was decreased significantly in the sample I group (P<0.05) compared to the control group; there was not significant effect in the sample II and sample III groups. 2. The moving distance of carbon bolus was increased significantly in the sample n (p<0.05) and sample II (p<0.05) groups compared to the control group; there was not significant effect in the sample I group. 3. The intestinal mobility index was increased significantly only in the sample II group (P<0.05) compared to the control group. 4. The feces consistency was increased significantly on the 3rd and 5th day of the sample I group (P<0.05), on 3rd, 4th, and 5th day of the sample II (p<0.05) and the sample III (p<0.05) groups compared to the control group. 5. The feces property index was increased significantly only on the 5th day of the sample III group (p<0.05) compared to the control group. 6. The number of WBC and RBC, levels of hemoglobin and hematocrit were not changed in all sample groups compared to the control group. 7. The number of the type B Goblet cells were increased significantly in the sample II (p<0.05) and the sample III (P<0.05) groups, but the number of the type C Goblet cells were decreased significantly only in the sample ill group (P<0.05) compared to the control group. Conclusions: According to the above results, GamiYijin-tang compared to the Yijin-tang were decreased hight significantly in gastrointestinal mucose and histological antidiarrheal function with protection of the goblet cell more excellently were observed.