An aqueous viscoelastic composition is provided comprising at least one viscoelastic surfactant, and at least one hydrophobically modified polymer, which is formed from polymerization of ethylenically unsaturated monomers; has a number average molecular weight of from 1,000 to 100,000 Da; and to a level of at least 0.1 mole %, based on the amount of monomer units in the polymer, contains monomeric units each covalently bonded to a pendant, optionally alkoxylated, hydrocarbyl group having from 6 to 40 carbon atoms, said pendant, optionally alkoxylated, hydrocarbyl group being connected to the backbone of said hydrophobically modified polymer via a non-ester containing linking group.