It is widely accepted that oxidative modification of lowdensity lipoprotein (LDL) plays a pivotal role in the initiation and development of atherosclerosis. In the present study, we found that the MeOH and H2O extracts of the plant Ampelopsis cantoniensis, and its main constituent, myricetin, possessed significant protective effects on LDL oxidation induced by either a metal ion (Cu2+) or a free radical (AAPH).