Epidemiological studies show the existence of the negative linear correlation between low plasma high density lipoprotein (HDL) and frequency of coronary heart disease (CHD). The low HDL concentration is connected also with the increasing risk of vascular crash in central nervous system. Probably the main mechanism of antiatherogenic action of HDL is its participate in the reserve cholesterol transport. Four stages are included in this process: the transport of free cholesterol from cells to extracellular acceptors (HDL); estrification of HDL cholesterol; transport of cholesterol esters from HDL to VLDL and LDL and uptake of these lipoproteins and cholesterol esters in the liver. Tke key role in selective uptake in liver and its transport to cells plays scavenger receptor BI. It seems probably that it is also applied in mechanism of efflux of cholesterol from cells. To other properties of antiatherogenic action of HDL belongs its antithrombotic effect: inhibition of adhesion and aggregation of platelets and inactivation of plasma Va and VIIIa factors resulting from participation of HDL as cofactor in protein C activation. HDL prevents also atherogenic modification of LDL by connected with paraoxonase (PON1) activity.