GnRH is widely used in the embryo fertilization program (FIV) as one of the ovarian stimulation regimens. At the implantation window, GnRH agonists are known to have an effect on the endometrium directly or indirectly. GnRH estimated has a negative effect on the development of endometrial cells after ovarian stimulation. This study is to analyze the impact of GnRH agonist on ovarian stimulation procedures on receptor expression and endometrial cell apoptosis. The study sample was a stored biological material (BBT) from serum and the endometrial tissue of Macaca nemestrina. The total sample is 8 and divided into 2 groups, the stimulated and control groups. Each sample will be examined 2 types which are the enzyme-linked immunosorbent assay (ELISA) for serum and immunohistochemistry (IHC) for endometrial tissue. IHC was performed with anti-GnRH and caspase 3 antibody. Concentration is measured using an ELISA reader and then converts Optical Density (OD) to a concentration using SoftMax Pro Software. Calculations of stained and unmarked cells were performed using the Image-J Analyzer programs and scored by HSCORE. There is no significant difference between GnRH serum in stimulation or control group (p=0.773). There was no correlation between GnRH in serum with GnRH receptor in endometrial tissue (p=0.060) and activation of caspase (p=0.193). There was no difference between stimulation group and control group in the amount of GnRH in serum, presence of active GnRHR, and Caspase 3 activation. Keywords: GnRH receptors, Macaca nemestria, GnRH Agonist, Controlled ovarian stimulation.