Xiong Y, et al. – This article was written with the objective to explore the impacts of high P level on the day of hCG administration in IVF cycles on epigenetic modifications of endometrium in the peri–implantation period. High P level on the day of hCG administration in IVF cycles influences epigenetic modifications in three compartments of endometrium in the peri–implantation period. The epigenetic markers' expression was mainly related to P level. The altered epigenetic modification status in the endometrium may disrupt the endometrial receptivity in women with high P on the day of hCG administration.