Objective : These experimental studies were designed to investigate the effects of Sargassum extract and Polygoni multiflori radix extract on the weight and the lipid metabolism of the obese rats induced by 1% cholesterol diet. They were designed to detect changes in the serum and leptin levels in the infant rats. Methods : The serum and leptin levels were measured for a period of 8 weeks for obese SD rats induced by 1% cholesterol diet. Result : 1. The body weight showed a tendency to decrease in samples I & II(P>0.05). 2. The average size of the epididymal fat cell significantly decreased in sample II(p<0.05), and showed a tendency to decrease in sample I(P>0.05). 3. The leptin levels significantly decreased in samples I & II(P<0.05). 4. The total cholesterol levels significantly decreased in samples I & II(P<0.05). 5. The triglyceride levels significantly decreased in sample I & II(P<0.05). 6. The glucose levels significantly decreased in sample I & II(P<0.05).