The invention relates to an extract of the plant Ajuga turkestanica containing at least one ecdysteroid and at least one iridoid and obtainable by extraction of at least part of said plant by means of a solvent or solvent mixture consisting of 0 to 60% by weight of water, the remainder of said solvent or solvent mixture consisting of at least one C.sub.1 to C.sub.4 alcohol and/or acetone and/or butylene glycol and/or propylene glycol, and very particularly to an extract containing one part by weight of ecdysteroids to 2 to 4 parts by weight of iridoids.The invention further relates to cosmetic uses of these extracts or associations containing one part by weight of ecdysteroids to 2 to 4 parts by weight of iridoids as cosmetic agents for improving the differentiation of keratinocytes, for regulating the water fluxes and the water absorption in the epidermis or for hydrating the epidermis.The invention further relates to a method of cosmetic skin treatment in which a cosmetically effective amount of the extracts or associations defined above is applied.