The homebox(HOX) proteins, as the highly conserved transcription factors, determine some body characteristics in many species,including human. HOXA10 is directly involved in the embryogenesis and embryo implantation in uterus by regulating the downstream genes, and estrogen and progesterone levels. In accord with hormones regulation, expression of HOXA10 gene in endometrium has a periodic profile, with the peak expression during the implantation window. Expression of HOXA10 gene in ectopic endometrium is one of important factors related with the de novo development of endometrial tissue. There are many factors, which influence embryo implantation, in ectopic endometrium of patients with endometriosis(EMs). It is well known that the embryo implantation failure is one of the main factors of infertility in EMs patients. EMs patients usually do not have the increased expression of HOXA10 in mid-luteal stage, which is one of the reasons of infertility.