The mechanism of interaction of hypochlorite and hypobromite formed in myeloperoxidase catalysis with lipids of human blood low-density lipoprotein is described. Both agents react with unsaturated lipids via two mechanisms: molecular (with the formation of mainly chloro- or bromohydrins and lysophospholipids) and free-radical (paralleled by lipid peroxidation). These reactions modify physicochemical properties of low-density lipoproteins and disorder their lipid-transporting function thus initiating early stages of atherosclerosis development.