Introduction: The aim of this study was to determine mouse endometrium glycocalyx cell surface alteration after ovarian hyperstimulation using hMG, hCG and daily progesterone injection at implantation time. Materials and Methods: For this purpose adult NMRI mice were super ovulated using hMG, hCG and then daily injections of progesterone (1 mg/mouse) performed in one group. The animals were sacrificed by cervical dislocation 3.5 and 4.5 days after hCG injection. Tissues were obtained from 1/3 middle part of uterine horns and processed for light and transmission electron microscopic studies. Results: Our results showed that the intensity of PAS reaction on surface epithelium of the control and the hyperstimulated groups increased 4.5 days after mating or hCG injection, but in the hyperstimulated and progesterone injected group there were intense PAS reaction on the 3.5 day after hCG injection. A well defined glycocalyx was observed on the epithelial cell surface of the control group and the hyperstimulated group, there were a lot of long cylindrical microvilli on their epithelium but after progesterone injection some of the microvilli and glycocalyx disappeared and there were some cytoplasmic projections. Conclusion: Thus ovarian hyperstimulation caused alteration in the glycocalyx and these changes may affect the electrical charge of the endometrium at the implantation period. Thus these changes could have influenced endometrial receptivity.