Provided is a cosmetic method by topical route for treating and/or preventing unpleasant human body odours, which comprises applying, to the surface of a human keratinous substance, a composition comprising, in a physiologically acceptable medium, at least one monounsaturated fatty acid or one of its salts and/or one of its esters and/or one of its amides. Also provided is a cosmetic method by the oral route for treating and/or preventing unpleasant human body odours, comprising ingesting an oral composition comprising, in a physiologically acceptable medium, at least one monounsaturated fatty acid or one of its salts and/or one of its esters and/or one of its amides.
