Sodium-aluminium silicates of a high degree of dispersion were obtained. Studies on the surface modification of sodium-aluminium silicates using silane coupling agents are described. The best modifiers, which induced a change of the silicate surface from a hydrophilic to a hydrophobic one, were selected. Physicochemical analyses of the obtained silicates were performed. The methods of evaluating the degree of surface modification of the silicate are presented. Attempts were made to employ the unmodified and modified sodium-aluminium silicates as fillers in polyurethane elastomers. The introduction of sodium- aluminium silicate into urethane elastomer induced increases in composite parameters such as tensile strength, relative elongation, and hardness. The most pronounced reinforcing effects were observed with urethane elastomers filled with sodium-aluminium silicate modified with an aminosilane (A-1120).