Abstract: The long GnRH agonist protocol has been widely used during controlled ovarian hyperstimulation （COH） for in vitro fertilization and embryo transfer （IVF-ET）. It is clear that gonadotropin-releasing hormone agonist（GnRHa）was used to prevent the premature LH surge related to worse follicles and higher cancellation rate. GnRHa may affect the endometrium at the molecular level, which may be responsible for endometrial receptivity. Those factors and cytokines related with endometrium receptivity, such as integrinανβ3 and TGF-β, were discussed. Effects of GnRHa on the endometrium ultrastructure and granular cell apoptosis were also discussed. However，the role of GnRHa in endometrial endocrine，embryo invasion，and subsequent pregnancy remains controversial. This review on the GnRHa strategies during COH could help clinicists to design the rational and individual protocol of GnRHa.

Key words: Reproductive techniques, assisted, Gonadotropin-releasing hormone, Endometrium, Integrins, Transforming growth factor beta, Pinocytosis, Granulocytes, Apoptosis