not-yet-known not-yet-known not-yet-known unknown ABO blood group antigens (namely, A, B, and H antigens) are carbohydrate epitopes on cell surface that play important roles in biological processes and diseases. The structure diversity of ABH antigens structures is associated with susceptibility to different pathogen infections. Advanced synthetic methodologies are required for studying and applying ABO blood group antigens. The existing methods include chemical, enzymatic and chemoenzymatic synthesis. As an alternative approach to chemical synthesis, enzymatic synthesis provides a simple pathway to access oligosaccharide antigens under extremely mild reaction conditions, thereby avoiding laborious protecting group manipulation procedures. Enzymatic synthesis of human blood group antigens primarily relied on Leloir glycosyltransferases, alongside several glycosidases and glycoside phosphorylases. This review aims to discuss recent advancements in chemical, enzymatic and chemoenzymatic synthesis of human ABH antigens, with a particular focus on novel developments in enzymatic assembly of naturally occurring ABH antigens.