Progesterone (P4) increases on the day of hCG administration in Controlled Ovarian Hyperstimulation (COH) procedure has reduced the rate of pregnancy in Assisted Reproductive Technology (ART). The aim of the study was to analyze the effect of the increase in P4 on the day of hCG administration to the expression of progesterone receptor (PR). Method: 15 samples of Macaca nemestrina endometrial tissue, in the form of stored biological materials, originated from groups of natural cycles and cycles stimulated in the COH procedure. For 16 endometrial tissue samples, PR expression was measured by immunohistochemical (CPI) technique. The level of PR expression was compared between the natural cycle and the stimulated cycle that got P4≥1 ng/mL and P4 <1 ng/mL. Results: PR expression was detected in three endometrial compartments, which were glandular cells, epithelial luminal cells and stroma. Semi-quantitative analysis used the formula H-SCORE = ςpi (i + 1). PR expression in the gland epithelium from natural cycle group and stimulated cycle with P4≥1 ng / mL and P4 <1ng / mL respectively 2.85 vs, 2.82 vs 2.43. The Kruskal Wallis test, PR expression in the glandular epithelium in the three groups was statistically different (P <0.05). PR expression in and between P4 <1 ng / mL with P4≥1 ng / mL in the stimulated cycle, it did not differ statistically (P > 0.05). Then, PR expression between P4 in the natural cycle with P4 <1 ng / mL in the stimulated cycle there was no significantly different (P > 0.05). PR expression in the luminal epithelium and stroma, between natural cycles and stimulated cycles was also not significantly different (P > 0.05). Conclusion, the level of P4 > 1 ng / mL on the day of administration of hCG in the COH procedure decreases PR expression in the endometrial gland.