To clarify the food value and physiological functions of carrot leaves, which are normally discarded, we measured the polyphenols in carrot leaves and their DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity, and further studied their effect on serum lipids in rats on a high cholesterol diet.    Carrot leaves contain protein, lipids, ash, total vitamin C and alimentary fiber at levels greater than the roots. The polyphenol contents were the highest in the boiled leaves. DPPH radical-scavenging activity was higher in the leaves than in the roots. There was no difference between any of the groups with regard to the various measured values in rat serum, but the total serum cholesterol and serum phospholipids were lower in the group receiving the leaves and roots than in the group receiving a high cholesterol diet. The ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity showed a high value in the group receiving the roots.    These results suggested that carrot leaves have just as much nutritional value as the roots, and since they are a food item with a physiological activity, they can be effectively used instead of being discarded.