Lecithin cholesterol acyl transferase (LCAT ) esterifies free cholesterol and is a key enzyme in the formation of plas - ma high density lipoproteins. It may also crucial in macrophage reverse cholesterol transfer . It has long been believed that LCAT activity is atheroprotective, but studies on the effect of LCAT on atherosclerosis are still highly controversial . Part of the controversy may be ex - plained by the difference in study design ,but the role of LCAT in atherogenesis is far from being fully understood . For population -based studies, the current methods for the measurement of LCAT activities are highly variable and may have different biological meanings . Reliable measurement of LCAT that effectively reflects the in vivo activities is needed for elucidating the relation between LCAT and ather - osclerosis and for the risk analysis of cardiovascular diseases .