To investigate the effect of GyeongshinhaeGihwan 1(GGT1) frequently used as an anti-obesity herbal medicine in oriental medicine on the expression of obesity-related genes, we measured the changes in mRNA levels of these genes by GGT1 in human growth hormone transgenic (hGHTg) obese female rats, and these effects by GGT1 were compared with those of reductil (RD), an anti-obesity drug approved by FDA. Rats received once daily oral administrations of autoclaved water, RD, or GGT1 for 8 weeks. At the end of study, rats were sacrificed and tissues were harvested. Total RNA from adipose tissue, liver and kidney was prepared and the mRNA levels for LPL (lipoprotein lipase), $PPAR{gamma}$ (peroxisome proliferator activated receptor-gamma), $PPAR{delta}$ (peroxisome proliferator activated receptor-delta), leptin, $TNF{alpha}$ (tumor necrosis factor-alpha), and internal standard G3PDH (glyceraldehyde-3-phosphate dehydrogenase) were analyzed by RT-PCR. Compared with control group, $PPAR{gamma}$ mRNA levels of liver and kidney were decreased in both RD and GGT1 groups, and the effects were more prominent in GGT1 group than in RD group, suggesting that GGT1 is effective in the inhibition of lipid storage by decreasing the $PPAR{gamma}$ expression. $PPAR{delta}$ mRNA levels of adipose tissue were increased by RD and GGT1 compared with DW, and the magnitude of increase were higher in GGT1 group than in RD group, indicating that GGT1 stimulates fatty acid oxidation and energy metabolism by activating $PPAR{delta}$ expression. GGT1 group had higher concentrations of serum leptin, a well-known inhibitor of appetite, than control and RD groups. However, The mRNA levels of leptin, LPL, and $TNF{alpha}$ were not changed by GGT1. These results indicate that GGT1 can prevent obesity in hGHTg obese female rats by down-regulating and up-regulating the mRNA expression of $PPAR{gamma}$ and $PPAR{delta}$, respectively, and that this anti-obesity effects were more pronounced in GGT1 group compared with RD group. In addition, GGT1 seems to inhibit obesity by increasing the circulating leptin levels.