Objective:To examine the anti-obesity effects of ginsenosides in Korea Red Ginseng (KRG,Panax ginseng) in rats fed with a high-fat diet (HFD).Methods:Twenty-five 4-week-old obesity rats after receiving an HFD for 5 weeks;subsequently,they were additionally treated with ginsenosides Rb1,Rd,Rg1,or Re (10 mg/kg,intraperitoneal injection) for a further 3 weeks (n=5 in each group).The control rats were fed a normal diet.The food consumption,body weight,locomotor activity,serum lipids,adipose tissues,nitric oxide (NO) expression,leptin,neuropeptide Y (NPY),cholecystokinin (CCK) in the brains were measured.Results:In the HFD-fed rats,body weight,body fat mass,serum levels of leptin and NO were significantly higher than in the control rats (P＜0.05 or P＜0.01).However,the treatment of Rd,Re,and Rb1 markedly decreased body fat mass and body weight (P＜0.05).The serum level of leptin and NO in ginsenoside-treated rats were markedly lower than the control group (P＜0.01).The expression of NPY and CCK in the hypothalamic nuclei showed insignificant difference among groups.However,the expression of NPY immunoreactive neurons in the hypothalamus was significantly reduced in the Rb1-treated group (P＜0.05).Conclusion:PD-type ginsenoside Rb1 from the crude saponins of KRG may be a useful compound for the treatment of obesity and related disorders through the modulation of peripheral and central appetite-regulating signals.