Abstract: There are disclosed aqueous dispersions of salts, e.g., tertiary amine salts, of polyamine-extended, aromatic polyisocyanate-based prepolymers having carboxylic groups, especially such dispersions made from prepolymers of polyisocyanates in which the isocyanate groups are on different aromatic rings. These products, as well as, aqueous dispersions of salts of prepolymers of aromatic polyisocyanates can be made from blocked, aromatic polyisocyanate-based prepolymers, particularly oxime-blocked prepolymers. The polymer salts can have sufficient neutralized, carboxylic groups to provide stable, aqueous dispersions, and the dispersions of the polyamine-extended polymers have infinite dilutability with water and excellent resistance to gelling upon freezing and thawing. Carboxylic groups can be supplied to the prepolymers by reactants having two or more groups containing isocyanate-reactive hydrogen atoms employed in making the aromatic isocyanate prepolymers, particularly dihydroxy alkanoic acids.