Résumé : Aggressive chemotherapy generally results in the loss of both endocrine and reproductive functions. If the patient has not undergone previous oocyte, embryo or ovarian tissue cryopreservation, orthotopic allotransplantation of fresh ovarian tissue from a genetically non-identical sister may be considered. Here, we describe a case report. The patient, aged 15 years and presenting with homozygous sickle cell anemia, underwent chemotherapy (busulfan, cyclophosphamide) and total body irradiation before bone marrow transplantation, the donor being her HLA-compatible sister. HLA group analysis later revealed complete chimerism. When the patient was 32 years old, ovarian allografting was performed, with the ovarian tissue donor being the same sister who had already donated bone marrow. The goal was to restore ovarian activity and natural fertility. No immunosuppressive therapy was administered. No sign of rejection was observed. Restoration of ovarian function was achieved 3.5 months after transplantation, as proved by the first estradiol peak and follicular development detected by ultrasound. After 9 months of regular ovulatory cycles, IVF was attempted because proximal tubal stenosis (unknown at the time of grafting) could not be repaired by tubal reanastomosis. After stimulation, three oocytes were retrieved. Two embryos were obtained. One embryo was frozen and the other was transferred, resulting in an ongoing pregnancy. The patient delivered a healthy baby girl weighing 3.150 g at 37 2/7 weeks of gestation.