At the time of implantation, the decidua is infiltrated by a unique population of NK cells with large granular lymphocyte morphology, which are thought to influence placental trophoblast invasion and differentiation. The mechanisms used by these cells to migrate within decidua are not known, but in other biological processes such as wound healing and tumor invasion cell-matrix interactions are important. These interactions are mediated by specific receptors, mostly belonging to the family of integrins. Decidual NK cells are observed to bind to type IV collagen and fibronectin, but not to laminin. Adhesion to collagen was inhibited with an anti-alpha 1 integrin subunit mAb, whereas adhesion to fibronectin was blocked with anti-alpha 4, -alpha 5, and -beta 1 integrin subunit mAbs. Binding of decidual NK cells to decidual stromal cells was partially blocked with mAbs to the alpha 4 and alpha 5 integrin subunits. These results provide insight into the possible mechanisms utilized by decidual NK cells for migration and retention within the pregnant uterine mucosa.