This study was performed to investigate the anti-obesitic effect of mulberry root-bark on male and female Zucker FA/FA or FA/fa rats. Obesity in the rats was induced by feeding high-lipid diet contained 3% corn oil and 1% cholesterol. Experimental groups in male and female rats were assigned to normal diet group (normal control), high-lipid diet group(positive control) and 3% mulberry root-bark powder in high-lipid diet group (MRC). The mulberry treated-group showed decreases of body weight, FER (food efficiency ratio) value and lipid peroxidation in the liver and increase of high density lipoprotein cholesterol (HDL-C) value, compared with positive control groups. Our findings suggest that mulberry root-bark has a potential role in preventing or improving obesity from the following points of view, body weight, serum lipids and antioxidant enzyme activities.