This invention relates to novel aqueous emulsion polymers obtained by free-radical initiated addition polymerization of at least one monomer in the presence of degraded starch and at least one polymeric emulsifier from the series of sulfo-containing maleic anhydride copolymers and/or sulfo-containing oligourethanes with a branched molecular structure. The invention further relates the use of such emulsion polymers as surface sizing agents for paper and paperlike materials.