Two cases of β-thalassemia major treated with fetal liver transplanta-tion(FLT)were reported.A conditioning regimen of total body irradiation pluscyclophosphamide was given,followed by the infusion of suspensions of fetal livercells.The number of nucleated cells(procared from 3 to 4 fetal livers)infused tothe 2 cases was 17.5 and 15.5×10~8/kg respectively.Transient hemopoieticdepression was observed after FLT,and normal hemopoiesis was recoveredaround the 30th day.Karyotypic analysis revealed that the donor typechromosomes was founed in the peripheral blood of both cases from the 20th dayto 123rd day after FLT.Skin biopsy of cass 1 revealed changes of mild GVHD,indicating engrafment of fetal hemopoietic cells and formation of chimeras in thisperiod.Autologous hemopoiesis was reconstituted in both cases two months afterFLT.Blood transfusion was not necessary within the first 5 months after FLT,and in case 1 transfusion was given 3 times only within 21 months after FLT. Two cases of β-thalassemia major treated with fetal liver transplanta- tion (FLT) were reported. Conditioning regimen of total body irradiation plus cyclophosphamide was given, followed by the infusion of suspensions of fetal liver cells. The number of nucleated cells (procared from 3 to 4 fetal livers) infused tothe 2 cases was 17.5 and 15.5 × 10 ~ 8 / kg respectively. Transient hemopoietic depression was observed after FLT, and normal hemopoiesis was recoveredaround the 30th day. Karyotypic analysis revealed that the donor type chromosomes was founed in the peripheral blood of both cases from the 20th day to 123rd day after FLT. Skin biopsy of cass 1 revealed changes of mild GVHD, indicating engrafment of fetal hemopoietic cells and formation of chimeras in this period. Autologous hemopoiesis was reconstituted in both cases two months after FLT. Blood transfusion was not necessary within the first 5 months after FLT, and in case 1 transfusion was given 3 times only within 21 months after FLT.