The work presented in this paper focuses on the effect of sodium dodecycl benzene sulfonate (SDBS) on the rheological behaviour of specific modified hydrophobically assocaiting polymer (HAP) aqueous solutions. The viscosities of polymer solutions from dilute, unentangled, semi-dilute, and entangled semi-dilute regimes were examined as a function of shear rate and SDBS concentration. It was found that SDBS enhanced the shear thickening in the entangled semi-dilute regime. The result was explained in terms of the balance between inter- and intra-chain liaisons and the effect if SDBS on the chain dimensions of the polymer. Fluorescent data showed that SDBS was associated with the hydrophobic groups of the polymer, generating a number of microdomains. These microdomains strengthened the structure viscosity of the polymer solutions. The addition of SDBS to the HAP solution also helped build up a reversible molecular structure and even a temporarily three-dimensional network in aqueous solutions via binding SDBS with hydrophobes of the polymer chains. The network structure resulted in a significant increase in viscosity of the polymer solutions. Consequently, thew SDBS/HAP systems could be used as thickeners for the fluids used in EOR processes.