The present invention relates to a composition for washing keratinous materials which comprises, in a cosmetically acceptable aqueous medium, particles essentially consisting of aluminium oxide and having a mean primary size in numerical terms of less than 200 nm, at least one anionic surfactant and at least one amphoteric or nonionic surfactant. The invention also relates to a method for the cosmetic treatment of keratinous fibres, as well as a use of the composition according to the invention as a shampoo.