The feeding effects of Rosa rugosa roots powder extracted with two different extracting solvents on lipid metabolism in rats were evaluated. Rats were fed with purified diets containing methanol or 70% aqueous acetone extracts at a 1% level for 4 weeks. In addition, to examine the effects of age, rats with different ages (4weeks old vs. 3 months old) were fed with purified diets containing methanol extracts at a 1% level for 4weeks. Feeding of methanol extracts decreased the concentration of triacylglycerol in serum and liver, whereas the aqueous acetone extracts lowered the concentration of liver triacylglycerol with concomitant elevation of the concentration of serum triacylglycerol. The methanol extracts ameliorated the degree of increase in the serum triacylglycerol level in relation to age and decreased especially the concentration of free fatty acid in serum of adult rats. The results suggested possibility that the regulatory mechanism responsible for triacylglycerol-lowering effects of Rosa rugosa roots extracts in the liver could be modulated by differences in the components of extracts due to the variation in extracting solvents, and that the methanol extracts might be effective in lowering an age-dependent increase in the concentration of serum and liver triacylglycerol in rats.