The invention relates to hair treatment agents containing, in relation to the total weight thereof: 0.001 to 4.9 % by weight polyurethane, obtained by reacting at least one polyurethane prepolymer A) containing isocyanate groups with at least one compound B) containing amino groups; and at least one specific quaternary ammonium compound Q. Said agents are characterised by an improved treatment action on keratin fibres.
