The influence of chorionic gonadotropin (CG) and estriol (Е3) at the concentrations typical of pregnancy on the expression of phenotypic markers and cytokine production by separated NK cells has been studied. It has been found that these hormones increase the percentage of CD56bright L-selectin+ NK cells, but also stimulate the expression of the inhibitory molecule NKG2A in the lymphocytes. In addition, Е3 and CG stimulate the production of TGF-β, inhibiting the secretion of all other cytokines by separated NK cells. In general, these hormones contribute to the formation of the phenotype and cytokine spectrum characteristic of the regulatory NK3 subpopulation of NK cells during pregnancy.