Isocyanate-free polyurethanes were synthesized by reaction of an oligomeric condensation product of urea, CH2O and p-HOC6H4SO3H with oligooxyalkylene dicarbamates, dispersed in water and used for impregnation of wet leather wastes to improve their hygienic and strength properties. Use of the oil in water dispersions was more efficient than the use of water in oil ones. The leather impregnated with polyoxybutylene urethane showed better properties than that impregnated with polyoxypropylene urethane.