Luteal estradiol pretreatment (LEP) to IVF protocols designed to improve follicle synchronization and retrieval of mature oocytes. We conducted a retrospective study including women undergoing IVF program who were given a course of 4mg oral estradiol-17b daily from day 20 of the same cycle until day 1 of their next cycle before starting an antagonist protocol, forming LEP-group but control-group started on day 3 a stimulation without pretreatment. A total is divided into 2 groups (poor (group 1, n¼148) and normal responders (group 2, n¼244)). Our findings show for group 1 a significant decrease in cancelation rate (3% vs 14%) and a significant improvement in clinical outcomes (clinical pregnancy per transfer and live birth rate respectively: 47% and 44% vs 12% and 11%). For group 2, this pretreatment could increase significantly the maturation rate (77% vs 68%). The rate of frozen embryos was improved in both groups: (group 1: 11% vs 2% and group 2: 53% vs 41%). LEP increases the frozen embryos rate whatever the nature of the ovarian response, but especially for normal responders it coordinates follicular recruitment increasing the maturation rate. In the case of poor responders, it affects positively clinical outcomes decreasing the canceled cycles.