A 16-year-old Sardinian girl affected by homozygous beta-thalassaemia was submitted to allogeneic BMT using an HLA-identical, MLC-negative, unrelated donor. The donor and the patient were homozygous for the entire extended haplotype A30, Cw5, B18, F130, DRB1*0301, DRB3*0202, DQA1*0501, DQB1*0201 and heterozygous for DPB1*0301/DPB1*0202. The conditioning regimen consisted of 14 mg/kg busulphan and 160 mg/kg cyclophosphamide. Engraftment was achieved 14 days from BMT and the haematological reconstitution was complete without any signs of acute or chronic GVHD. Seven months after the transplant the patient was in excellent general condition. The hypothesis is advanced that when two HLA extended haplotypes are shared by donors and recipients, particularly in homozygosity, this is a very favourable immunogenetic condition in unrelated BMT.