Lectine-carbohydrate interactions take the fundamental part in the intercellular relations as well as in microbes pathogenicity. Pathogenic Mollicutes are characterized by the firm adhesion to the cells of the affected organs of people, animals, insects and plants. Proteins which are localized on the external side of the mollicute membrane and interact with carbohydrate residues on the surface of mucous membranes of the damaged organs and vice versa take part in the adhesion. High degree of specificity of protein-carbohydrate interactions determines the pathogenic specializations to the cells of one or another organ of the host. Since proteins which take part in the mollicutes adhesion are rich in proline and hydrophobic fields it is not excluded that the adhesion processes are combined with hydrophobic interrelations between the cells of the pathogen and host. Substances from the cells of Mollicutes which completely correspond to the definition "lectin", i.e., are in a pure form, the carbohydrate-binding proteins specific to certain carbohydrate residues are not still isolated. Thus the mollicute lectines should be called lectine-like substances rather than lectines. Mollicutes form a lot of such substances and they may be separated into the extracellular (soluble) substances which are found outside the cell of the nutritious medium; intermediate (half-soluble) substances detected in the nutritious medium and in the state integrate into the microorganism membrane, and membrane-related (insoluble) substances which occur only in the state rigidly adhered to the membrane. Carbohydrate composition of lectine-like substances in different mollicutes is different which is the reflection of heterogenicity of the Mollicutes class representatives.