We review recent studies of two cytokines IL-15 and IL-18, showing that they are the critical cytokines controlling uterine NK cell cytokine production and cytolytic potential. Further, IL-15 has been implicated in differentiation and proliferation of uterine NK cells, while IL-18 enhanced innate immunity and both Th1- and Th2-driven immune responses depending on the cytokine milieu. We addressed the possible role of these two cytokines in induction of the IFN-gamma production as a key molecule in vascular remodeling during early pregnancy.