 Oocyte donation is a well established procedure in assisted reproduction treatments ART. It is demonstrated that the use of hormonal substitution therapy, for the synchronization of the cycles between the recipients and the donors, provides good results, similar to the ones obtained with the natural cycle. In the patients - recipients with preserved ovarian function, the recipients natural cycle is annulled, thus preventing the spontaneous Luteinizing Hormone surge. Simultaneously and while waiting for the suitable donor, her endometrium is prepared. When the donation occurs and fertilization with the husband sperm takes place, her cycle is stimulated again in order to synchronize her window of implantation with the donors ovulation. 