**Abstract**

The window of implantation has long posed as a challenge in understanding the exact synchronized cross talk that must take place in order for a developing embryo to be appropriately received by the endometrium. This is due mostly to the fact that it is difficult to study human models of implantation without sacrificing the potential for pregnancy. For many who present with a diagnosis of infertility with an otherwise unexplained etiology, recurrent implantation failure or a displaced window of receptivity may be an underlying, silent cause. As assisted reproductive technology (ART) continues to advance and offer new scientific breakthroughs allowing greater insight and understanding to reproductive failure and infertility, endometrial receptivity testing may offer answers to struggling patients.

**Keywords:** window of implantation, uterine receptivity, endometrium, blastocyst, embryo
