The invention relates to radiation-curable aqueous composition comprising an ethylenically unsaturated polyurethane pre-polymer obtained from the reaction of a polyisocyanate, a high molecular weight polyol, at least one hydrophilic compound containing at least one reactive group capable to react with isocyanate groups and which is capable to render the polyurethane pre-polymer dispersible in aqueous medium either directly or after the reaction with a neutralizing agent to provide a salt, an ethylenically unsaturated compound containing at least two reactive groups capable to react with isocyanate groups and an ethylenically unsaturated compound containing essentially one reactive group capable to react with isocyanate groups, said composition comprising an amount of polymerizable ethylenically unsaturated groups of at least 3 meq per g.
