A new inhibitor named elatosides E (which was shown to affect the elevation of plasma glucose level by oral sugar tolerance test in rats) was isolated from the root cortex of Aralia elata SEEM. together with elatoside F. The structures of elatosides E and F were elucidated on the basis of chemical and physicochemical evidence. The hypoglycemic activities of oleanolic acid and nine oleanolic acid glycosides obtained from the root cortex of Aralia elata heve been examined, and some structure-activity relationships have been found.