A composition for washing a keratinous substance comprising, in a cosmetically acceptable aqueous or aqueous/alcoholic medium, at least one linear block copolymer comprising at least one hydrophobic block and at least one hydrophilic block, with the exception of block copolymers of ethylene oxide and of propylene oxide, block copolymers comprising urethane units and block copolymers comprising siloxane units, at least one polymer chosen from cationic and amphoteric polymers, and at least one anionic surface-active agent in combination with at least one additional surface-active agent chosen from nonionic surface-active agents and amphoteric surface-active agents, and a method for washing keratinous substances, for example, keratinous fibers using said composition.