 Currently, available data suggest that inadvertent administration of a GnRH agonist during a conception cycle is not accompanied by an increased risk of birth defects. On the basis of the currently strong available evidence, it appears that GnRH agonist supplementation during luteal phase significantly improve the outcome of ART treatment. Most of the former researches focused only on fresh embryo transfer in IVFICSI cycles. In one prospective controlled study, a single dose of Triptorelin 0.1mg was administrated 6 days after ICSI in oocyte donor cycles and the implantation rate was improved significantly.GnRH agonist administration at the time of implantation enhances embryo developmental potential, probably by a direct effect on the embryo. 