Objectives: This study was designed to investigate the effect of Gami-cheongpyesagan-tang extract (GCST) on high fat diet-induced obesity in rats. Methods: The mice were divided into six groups; normal diet control, high fat diet control (HFD), HFD＋GCST administrated group (100, 200, and 400 mg/kg) and olistat-admistrated group. Obesity was induced by high fat diet (45%) for 7 weeks in mice, and GCST was administrated orally every day for 7 weeks. The body weight, food intake, and serological markers such as total cholesterol, triglyceride, lipid contents, leptin, adiponectin and glutamic oxaloacetic transaminase/glutamic pyruvic transaminase were measured in mice. The mRNA expression of obese-associating genes such as sterol regulatory element-binding protein (SREBP)-1c, fatty acid synthase (FAS), stearoyl-CaP desaturase (SCD-1), peroxisome proliferator-activated receptor (PPAR)-α, COA oxidase (ACO), and carnitine palmitoyltransferase (CPT-1α) was analyzed by reverse transcription polymerase chain reaction. Results: The administration of GCST at 400 mg/kg, significantly reduced the increase of bodyweight and food intake as well as food efficiency compared to HFD group. GCST decreased the serum levels of triglyceride, total cholesterol, low-density lipoprotein-cholesterol, leptin in HFD control group and inhibited lipid accumulation in liver and adipose tissues, but did not increase high-density lipoprotein-cholesterol. In the liver tissues of GCST administrated HFD group, the mRNA levels of SREBP-1c, FAS and SCD-1 were decreased and the mRNA levels of PPAR-α, ACO, and CPT-1α were increased. Conclusions: These results indicate that GCST could improve high fat diet induced obesity through inhibiting the hyperlipidemia in fatty Liver. It suggest that GCST may be used clinically for declining the accumultion of body fat with hyperlipidemia.