The adverse/deleterious signs or effects of skin aging, for example, wrinkles and fine lines, withered skin, flabby skin, thinning of the dermis, etc., are inhibited/treated by topically applying onto the skin, hair and/or mucous membranes of an individual subject in need of such treatment, a thus effective amount of at least one extract of at least one plant of the Rosmarinus genus, or cosmetic/dermatological composition comprised thereof.