Plasma lipoproteins are complex substances composed of certain ratios of lipids and proteins, and are important factors for serum lipids transportation. On the surface of the lipoprotein structure, apolipoproteins are present and playing roles in stabilization of lipoprotein structure, in activation of enzymes relating to lipoprotein metabolism, and in binding with lipoprotein receptors on the cell surface. Apolipoprotein-B48 (ApoB-48) has 48% amino acid sequence of apolipoprotein B-100 which is present in lipoproteins ,VLDL, LDL and HDL of liver origin. ApoB-48 is an apolipoprotein specific to a lipoprotein, chylomicron (CM) which is formed in intestine and carries exogenous lipids derived from foods to the liver and peripheral tissues. Measurement of ApoB-48 is useful in observation and pursuit of postprandial dynamics of lipoprotein, lipid-soluble nutrients and drugs.