The present invention relates to water-soluble hydrophobically associating copolymers which are obtained in the presence of a nonpolymerizable surface-active compound and which comprise novel hydrophobically associating monomers. The monomers comprise an ethylenically unsaturated group and a polyether block, the polyether block comprising a hydrophilic polyethyleneoxy block and a hydrophobic polyalkyleneoxy block consisting of alkyleneoxy units having at least 4 carbon atoms. The monomers may optionally have a terminal polyethyleneoxy block. The invention further relates to processes for preparing the copolymers and to the use thereof.