Effect of the amide solvent N-methylpyrrolidone occurring in polymer films after their formation on the physicochemical and transport properties of the membranes during pervaporation of a water-isopropanol mixture has been investigated in detail. The objects of study have been new polycarbamide-based membranes a prepared by solvent evaporation from polymer solutions and containing the residual solvent and the membranes from which the residual solvent was removed by special treatment. It has been shown that the removal of the residual solvent increases the density and decreases hydrophilicity of the membrane; in this case, the permeate flux decreases partly during the process of pervaporation, although the separation factor of the water-isopropanol mixture remains high. A composite membrane comprised of a thin selective layer of polycarbamide (similar to 6 mu m) and a porous polyphenylene oxide support designed to enhance the flux has been made and investigated.