Most children with acute lymphoblastic leukemia (ALL) are successfully treated by chemotherapy. For those patients, who relapse on therapy, bone marrow transplantation (BMT) is considered most appropriate after a subsequent remission is achieved. Three boys with ALL aged from 9 to 13 years met these criteria and received BMT from their HLA-compatible sisters after marrow ablation with total body irradiation 12 Gy plus high dose cytosine arabinoside 3 gm/m2/12h x 12 doses and graft-versus-host disease (GVHD) prophylaxis with cyclosporine plus short course methotrexate from March 10, 1989 to May 23, 1992. Filgrastim (rhG-CSF) was used to hasten the recovery of granulocyte in one patient. All three patients got full engraftment and two had grade 1 acute GVHD. None of them developed chronic GVHD. Two patients have disease-free survival over 51 and 12 months respectively post BMT without further chemotherapy. One patient died of recurrent refractory leukemia 5 months after BMT. The toxicity of this conditioning regimen included photophobia, conjunctivitis and erythematous skin rashes. One patient who received filgrastim from day 1 to 21 developed severe bone pain. However, this patient had faster recovery of granulocyte count than the other two patients. The preliminary results of this work favors BMT for children with recurrent ALL whose ultimate survival is usually poor when treated with chemotherapy. Further efforts are necessary to investigate new methods for reducing leukemic relapse in ALL patients undergoing BMT.