System of lipoproteins serves for the transport of fatty acids in the blood. Triacylglycerols are the transport form of saturated (mono-unsaturated and trans-forms) fatty acids forming crystal phase. Phospolipids and cholesterol ethers are transport forms of polyunsaturated acids in the polar and crystal phases, respectively. Even in the forms of complex lipids saturated and polyunsaturated fatty acids are transported in the blood by various apoproteins. ApoB-48 transports saturated fatty acids to hepatocytes in the form of chilomicrons. ApoA-1 transports transports polyunsaturated fatty acids directly to cells including hepatocytes. ApoA-100 contains two lipid binding domains. It transports saturated fatty acids and their cholesterol ethers associated with the third and fifth domains, respectively. For the structural function polyunsaturated fatty acids are transported by ApoA-1 high density lipoproteins in the polar phase and they penetrate into cells via phospholipid re-esterification.