Unmanipulated hematopoietic stem cell transplantation from haploidentical family donors is frequently associated with graft failure and severe graft-versus-host disease (GVHD). We employed a myeloablative conditioning regimen consisting of 125 mg/m2 of fludarabine, 140 mg/m2 of melphalan and TBI of 10 to 12 Gy for three patients. The donor in each case was a haploidentical two-loci HLA mismatch mother or son. Engraftment failure was observed in one patient. In the other two patients, engraftment was confirmed within 15 days after transplantation. Acute and chronic GVHD was observed, but was controllable in both cases. HLA mismatched transplantation based on feto-maternal tolerance may provide an alternative option for patients who do not have HLA-matched donors.