To investigate whether GyeongshinhaeGihwan 1(GGT1), an anti-obesity herbal medicine widely used in oriental medicine, regulates 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 male 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. PPAR$gamma$ mRNA levels of liver and kidney were decreased in drug-treated groups compared with control group and the decrease of PPAR$gamma$ expression was more prominent in GGT1 group than in RD group, suggesting that GGT1 is effective in the inhibition of adipogenesis and lipid storage by decreasing the PPAR$gamma$ expression. In contrast, PPAR$delta$ mRNA levels of adipose tissue and kidney were increased by RD and GGT1 , and the magnitudes 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, Compared with control and RD groups, GGT1 group had higher concentrations of serum leptin, a well-known inhibitor of appetite. However, The mRNA levels of leptin, LPL, and TNF$alpha$ were not changed by GGT1 and RD, compared with DW. These results demonstrate that GGT1 not only decreases PPAR$gamma$ expression of liver and kidney, but also increases PPAR$delta$ expression of adipose tissue and kidney, leading to the regulation of obesity and that these effects were more pronounced in GGT1 group compared with RD group. In addition, GGT1 seems to prevent obesity by increasing the serum leptin levels.