The invention relates to aqueous polyurethane dispersions that are curable with UV radiation. The polyurethanes are chain-extended with aromatic, cycloaliphatic or aliphatic diamine compound and cross-linked with aliphatic triamine compound. The polyurethanes are useful dispersions for coating various substrates. The use of the invented dispersions results in high hardness, very good flexibility and good chemical resistance in both clear coats and pigmented coatings before and after UV curing combined with very good adhesion to different substrates.