The advantages of polymer compositions based on urethane prepolymers with alkoxysilane groups in a molecular chain are associated first of all with the absence in the resulting oligomer of free –NCO groups. Their absence in a molecule extends the scope of application in the formulations of composite mate rials of rather effective amino and epoxysilane adhe sion promoters imparting highly valuable properties to these materials: the possibility of controlling adhesion to metals, glass, and other poorly gluing surfaces with low surface energy in wide ranges even without pre liminary priming of substrates [8] and the possibility of introducing sterically hindered amine stabilizers in order to increase the service life of compositions and provide high stability to UV irradiation. Introduction of such additives into conventional compositions based on urethane oligomers with free –NCO groups does not seem possible. Such factors as the absence of bubbles during curing, unlike urethane compositions with free –NCO groups, and the possibility of coloring of the cured material in particular with dyes on aque ous basis, which is impossible in a number of cases for common silicone compositions, are no less important.