Graft polymers of ketone-aldehyde condensation and co-condensation products and/or the monovalent or polyvalent metal compounds thereof are described, in which condensation product consists a) of symmetrical or asymmetrical ketones containing aliphatic, araliphatic, cyclic or aromatic hydro-carbon radicals with at least one nonaromatic radical, b) an aldehyde of the formula R--(CHO).sub.n, wherein n=1 to 2 and R can be hydrogen or an aliphatic, araliphatic, aromatic or heterocyclic radical, and c) optionally of carboxyl, sulpho, sulphamido, sulphoxy, sulphoalkylamine or sulphoalkyloxy groups, to which product anionic and/or nonionic and/or cationic unsaturated monomers have been grafted. These graft polymers are outstandingly suitable as dispersants for inorganic binder suspensions and solutions, for aqueous clay suspensions and solutions or coal/water suspensions, as retention agents, thickeners, in particular for aqueous systems, and as agents for preventing the swelling of clay in aqueous systems.