The aim of the present study is to investigate the effect of ethanolamine plasmalogens on the oxidative stability of cholesterol-rich membranes by comparing it with that of diacyl glycerophosphoethanolamine, using bovine brain ethanolamine plasmalogen (BBEP) or egg yolk phosphatidylethanolamine (EYPE)-containing large unilamellar vesicles (LUVs) and the water-soluble radical initiator AAPH. Electron microscopic observation and particle size measurement visually demonstrated that ethanolamine plasmalogens protect cholesterol-rich phospholipid bilayers from oxidative collapse. Lipid analyses suggested that the effect of ethanolamine plasmalogens in stabilizing membranes against oxidation is partly due to the antioxidative action of plasmalogens involved in scavenging radicals at vinyl ether linkage.