A subject-matter of the present invention is the cosmetic use, as deodorant active agent, of a monounsaturated fatty acid or one of its salts and/or of its esters and/or one of its amides, in particular in a composition comprising a physiologically acceptable medium. It also relates to a cosmetic method by the oral route for treating and/or preventing unpleasant human body odors, consisting in 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.