Human embryo implantation requires an activated blastocyst, a receptive endometrium and communication between the two. Implantation is initiated following apposition and firm adhesion to the endometrium where abnormalities in firm adhesion results in implantation failure and infertility. Very little is known of blastocyst-endometrial interactions in humans, largely due to the lack of appropriate models. We have developed a unique model to study the interactions and discovered that human embryos release certain non-coding RNA, that reflect their implantation potential following IVF. This may be useful as a non-invasive test for determining embryo implantation potential. Further we discovered that embryos secrete microRNA bound to Argonaut 1 which are taken up by human endometrial cells and regulate their adhesive capacity via altering specific proteins. There is very little known of the role of extravesicle microRNA in cell-cell communication. These studies could therefore have wide implications on the role of secreted microRNA in cell-cell communication in general in addition to their role in embryo implantation.