To determine the effects of Mahaengeuigam-tang(MHEGT) on obesity, the obesity-related factors (gastrin, CGRP, ghrelin, glucagon-like peptide-1, insulin, orexin, leptin, serotonin, NPY) were investigated in the stomach, pancreas, brain of mice by immunohistochemical methods for 4 weeks after Mahaengeuigam-tang(MHEGT) administration. The change of boy weight decreased in MHEGT administered group than that of control group. The immunohistochemical density of the gastrin and CGRP positive cells on pylorus of stomach increased in MHEGT administered group than that of control group. The number of ghrelin immunoreactive cells on stomach decreased in MHEGT administered groups than that of control group. The immunohistochemical density of GLP-1 in the pancreas decreased in MHEGT administered group than that of control group. The immunohistochemical density of insulin positive cells in the pancreas decreased in MHEGT administered group than that of control group. The immunohistochemical density of orexin and NPY positive neurons in the diencephalon was slightly stronger in MHEGT administered group than that of control group. The immunohistochemical density of serotonin and leptin positive neurons was stronger in MHEGT administered group than that of control group. These results demonstrate that Mahaengeuigam-tang(MHEGT) increased the immunohistochemical density of factors related to appetite inhibitors, and decreased the immunohistochemical density of factors related to stimulator of food intake in stomach, pancreas and brain.