The shear imposed oscillation technique was employed to probe the shear-induced structural changes of 3 wt% hydrophobically modified polyelectrolyte solutions that possess shear-thinning and shear-thickening behavior. The shear-thickening behavior is related to the transformation of predominantly intra-molecular to inter-molecular associations. On the other hand, the shear-thinning behavior under moderate shear deformation is caused by the re-organization of the transient network structure. Under high shear deformation, the shear-thinning behavior is solely caused by the shear-induced effect that increases the chain-end exit rate, which reduces the mechanically active chains and lifetime of the hydrophobe in the micellar junctions. (c) 2006 Elsevier Ltd. All rights reserved.