Cholesteryl linoleate hydroperoxides are derived from the autoxidation of cholesteryl linoleate and contain a mixture of racemic 9- and 13-HpODE cholesteryl esters. Oxidative modification of LDL is suggested to play an important role in atherosclerosis. (±)9- and (±)13-HODE cholesteryl esters were originally extracted from atherosclerotic lesions and shown to be produced by Cu2+-catalyzed oxidation of LDL. Later studies determined that 15-LO, from rabbit reticulocytes and activated human monocytes, oxygenates cholesteryl linoleate to both 9- and 13-hydroperoxy linoleate cholesteryl esters. Cholesteryl ester hydroperoxides may be transferred from LDL to HDL, reduced to the corresponding hydroxides, and cleared via the liver.