A carbohydrate antigen (CA) represents an immunogenic substance structurally based on saccharide units. These molecular markers exist on cellular surfaces across healthy and malignant tissues, where they mediate intercellular communication and immunological identification. Chemically, carbohydrates constitute polyhydroxy compounds encompassing aldehydic, alcoholic, ketonic, and acidic structures with their derivatives and macromolecular assemblies, fundamentally composed of carbon, hydrogen, and oxygen atoms. Their classification by polymerization degree distinguishes three categories: monomeric sugars, short-chain oligomers, and polymeric polysaccharides. Research confirms these biomolecules’ critical involvement in immune regulation, fertilization processes, hemostatic mechanisms, pathogen defense systems, and ontogenetic progression.