In westernised societies, atherosclerosis and its clinical consequences such as heart disease and stroke constitute the leading cause of death. Thus, the prevention or deceleration of atherogenesis is one of the most significant medical objectives since this is a matter of avoiding myocardial and cerebral infarction. Taken together, current knowledge recognises a whole range of indicators associated with atherosclerosis, including the relative concentration of various lipoprotein particles. Here, we propose to study the structure of lipoprotein particles at the surface of various components of the vessel wall. For this we will start with the well characterised heparan sulfate - LDL/HLD system to unravel the fate of the lipoprotein particle components in the heparan sulfate coated silica surfaces by means of neutron reflection. We start with lipoprotein particles from human blood.