We have discovered serum factor responsible for atherogenicity. This is multiple modified low density lipoprotein circulating in the blood of patients. I would like to specially emphasize that this modification is not only oxidative modification. I have no time to list all changes of lipoprotein particle in details. There are numerous physico-chemical characteristics which are altered in lipid, protein, and glycoconjugate moiety of lipoprotein particle. The most important property of multiple modified ldl is the ability to accumulate lipids in arterial cells.