As obesity is known to be related to hyperlipidemia, insulin and leptin resistance, and other chronic diseases, much recent research has focused on functional food materials and their anti-obesity activity. This study was performed to study the effects of Artemisia Iwayomogi oligosaccharide AIPI on the anti-obesity function in normal rats and diet-induced obese (DIO) rats. F344 male rats were divided into four groups: Normal-control (CONT), normal-AIPI, DIO-CONT and DIO-AIPI. The groups were provided with water (in the CONT groups) or another drink for 4 weeks. The final body weights of rats in the DIO-AIPI group were lower than those in the CONT group. Abdominal adipose tissue weight per kg of body weight in the DIO-AIPI group was significantly lower than that in the DIO-CONT group. Also, the final levels of serum-triglyceride, serum-total cholesterol and serum-low density lipoprotein cholesterol in the DIO-AIPI group were lower than those in the DIO-CONT group. Moreover, the serum-high density lipoprotein cholesterol level in the normal-AIPI group was significantly higher than that in the normal-CONT group. Finally, the serum-leptin concentration was significantly lower in the DIO-AIPI group. Total lipid, triglyceride, and total cholesterol contents in the feces of the DIO-AIPI group were as high as 142％, 199％, and 165% of the respective values of the DIO-CONT GROUP. These results indicate that orally administered Artemisia Iwayomogi oligosaccharide not only has hypotriglycemic and hypocholesterolemic effects, but also has the effect of reducing the body weight and the abdominal adipose tissue weights obese rats. Therefore, we expect that Artemisia Iwayomogi oligosaccharide AIPI may have an anti-obesity function in F344 diet-induced obese rats. (Korean J Nutrition 36(5): 437∼445, 2003)