Copolymers which are composed of at least 4 monomers, including (meth)acrylate compounds containing perfluoroalkyl groups, are suitable for the treatment of fiber materials. The copolymers are usually used here in the form of aqueous dispersions. The fiber materials are in particular fabrics, for example made of polyolefin. Treatment with the copolymers imparts to them oil- and water-repellent properties and also repellent properties toward low molecular weight alcohols.