The ABO blood group was discovered in 1900 by Austrian scientist, Karl Landsteiner. At present, the International Society of Blood Transfusion (ISBT) approves as 29 human blood group systems. The ABO blood group system consists of four antigens (A, B, O and AB). These antigens are known as oligosaccharide antigens, and widely expressed on the membranes of red cell and tissue cells as well as, in the saliva and body fluid. The ABO blood group antigens are one of the most important issues in transfusion medicine to evaluate the adaptability of donor blood cells with bone marrow transplantations, and lifespan of the hemocytes.This article reviews the serology, biochemistry and genetic characteristics, and clinical application of ABO antigens.