This chapter presents published data on the embryonic regulation of endometrial epithelial molecules such as chemokine receptors, the leptin system and the relaxin receptor LGR7. Chemokines and their receptors are divided into two families based on structural and genetic considerations. A specific molecular cross-talk between embryo and endometrium has been reported to take place during human implantation process. In human and rodents, two major forms of leptin receptors (OB-R) are expressed: the short form (OB-RS) and the long form (OB-RL). Relaxin is a peptide hormone produced by the corpus luteum during luteal phase of the menstrual cycle and during first trimester of pregnancy. It has been associated with a wide range of functions related to pregnancy, such as parturition and lactation. Advances in gene expression profiling facilitated by the development of DNA microarrays represent major progress in global gene expression analysis.