In this study, two monoclonal antibodies (McAb) against malondialdehyde-modified low density lipoprotein (MDA-LDL) were obtained, designated as HML1 and HML2 respectively, both of them can react to MDA-LDL with a high titer and belong to the subclass of IgG2a. The McAb additivity test shown that two McAb were against the same determinants of MDA-LDL. Solid-phase competitive biotinavidin EIA indicated that HML1 recognized MDALDL, MDA-alburnin, MDA-polylysine but not native LDL.It is postulated that the covalent aducts of MDA with lysine residues are involved the formation of MDA-derived epitopes on apolipoprotein B.