To investigate the efficacy and feasibility of parent non-T cell depleted haploidentical bone marrow transplants (haploidentical BMT) for children with leukemia, the efficacy of haploidentical BMT was evaluated in 8 leukemia children (1.9-9 years) received hematopoietic stem cell transplantation, donors were their parents with HLA-mismatched for two or three loci. Five children were pre-conditioned with a myeloablative regimen consisting of high-dose cytarabine (Ara-C), cyclophosphamide (CY) and total body irradiation. Busulfan (BU), Ara-C and CY were used for preconditioning regimen in other three children. The donors were given G-CSF prior to marrow harvest and the non-T-cell depleted grafts were used. A combination of CsA, MTX, ATG, mycophenolate mofetil (MMF) and CD25 monoclonal antibody were used for GVHD prophylaxis. The results showed that rapid engraftment was observed in all cases after transplantation by cytogenetic evidence. The mean time of neutrophil count exceeded 0.5 x 10(9)/L and the mean time of platelet count exceeded 20 x 10(9)/L were 16 and 17 days after transplantation respectively. Incidence of lethal aGVHD was lower, II-III acute aGVHD was found only in one out of eight patients. Chronic GVHD was observed in five patients, 4 from which showed local cGVHD, one developed extensive cGVHD. During the follow-up of 33 months (range 7-56 months), two patients died from relapsed leukemia, including one relapsed as donor-origin leukemia. Disease-free survival was achieved in the remaining six patients. No death occurred during the follow-up of 6 months. It is concluded that above-mentioned preconditioning regimen and GVHD prophylaxis procedure in non-T-cell depleted bone marrow transplantation from HLA-mismatched parents are effective approaches and safe strategy for the treatment of children leukemia.