A 5 year 9 month-old boy has received a bone marrow allograft for beta-thalassaemia major. Conditioning included busulfan: 16 mg/kg, cyclophosphamide 200 mg/kg and a (6 Gy) thoracoabdominal irradiation. After a 16 months follow-up, the child is currently in complete remission without treatment with all the markers of his donor. His 9 year-old sister has been allografted for beta-thalassaemia major, with the same conditioning regimen. After engraftment, rejection occurred at day 85 with severe aplastic anaemia. A second graft was performed with the same donor without engraftment and the patient died at day 18 of pneumonitis. A review of the literature is proposed and the ethical choices are discussed.