The biological actions of various ginseng extracts have been studied for treating obesity and diabetes mellitus. However, few studies have evaluated the effects of fermented Korean red ginseng (Panax ginseng Meyer) on metabolic syndrome. The present study evaluated the anti-obesity and anti-diabetic effects of fermented red ginseng (FRG) on old aged obese leptin-deficient (B6.V-Lepob, “ob/ob”) mice.