Oil- and water-repellent papers are treated on the surface or in the pulp of the papers with fluorine-containing copolymers of a) acrylates containing perfluoroalkyl groups, of the formula b) monomers of the formula c) monomers of the formula d) monomers of the formula or, in salt-like form, of the formula or, in N-oxidized form, of the formula ##STR1## and e) monomers of the formula these substituents and indices in the formulae having the meaning given in the description and the copolymers comprising the monomers in amounts of a) =50 to 90% by weight, b) =1 to 35% by weight, c) =3 to 20% by weight, d) =1 to 20% by weight and e) =0 to 10% by weight. Such copolymers having a content of e) =0.5 to 10% by weight are new.