Abstract: A water-based polyurethane dispersion is prepared by mixing an aliphatic diisocyanate with three critical active hydrogen compounds, to form a prepolymer containing carboxyl groups and free isocyanate groups, then dispersing the prepolymer in an aqueous medium containing a tertiary amine, which converts the carboxyl groups to carboxylate ions, and a diamine, which chain-extends the prepolymer through its --NCO groups. These aqueous dispersions are storage-stable for at least several months and are useful in many coating applications, among others, for coating textile materials.