A series of polyurethane + polyacrylate latexes has been synthesized by putting different quantities of polyacrylate dispersion into an acetone solution of an anionic polyurethane prepolymer with terminal isocyanate groups. Colloid-chemical and rheological properties of these systems have been investigated. The sorption of solvent vapors by mixtures of polyurethane + polyacrylate latexes has been studied. Some thermodynamical parameters including partial Gibbs functions of the solvent, individual polymers and their mixtures, and the Gibbs function of mixing polyurethane ionomer and acrylate copolymer have been calculated. Structure-properties relationships of the polyurethane + polyacrylate latexes were studied by dynamic mechanical analysis. Effects of varying the composition on the mechanical properties have been determined.