Recent developments in the field of water-soluble polymers aimed at enhancing the aqueous solution viscosity are reviewed. Classic and novel associating water-soluble polymers for enhanced oil recovery (EOR) applications are discussed along with their limitations. Particular emphasis is placed on the structure-property correlations and the synthetic methods. The observed theological properties are conceptually linked to the polymer chemical structure (1) and topology (2). In addition, the influence of external parameters, e.g. temperature, pH, salt, and surfactant, on the theological behavior is reviewed. Progress booked in deeper understanding of the structure-property relationship is thoroughly discussed. Furthermore, a critical overview of the synthetic methods as well as of the solution properties of these polymers is provided. In this respect the influence of "internal" (i.e. chemical structure) and "external" (vide supra) factors on these properties provide a conceptual toolbox for the rationalization of the response of water-soluble polymers to external stimuli. In turn, such rationalization constitutes the basis for the design of new polymeric structures for EOR applications. (C) 2011 Elsevier Ltd. All rights reserved.