Acute lymphoblastic leukemia of childhood is the most common malignant disease in children greater than 1 year of age. Chemotherapy has improved the survival of children with this disorder. More than 95% of children will achieve a remission with chemotherapy. However, 30% of children with acute lymphoblastic leukemia who achieved a remission will have a relapse sometime after successful remission-inducing chemotherapy. Although a second remission can be induced in most of these children, in 10-40% a remission cannot be induced or they relapse shortly thereafter and develop refractory leukemia. We present in this preliminary report the early results of therapy for refractory leukemia with an intensive preparative regimen for bone marrow transplantation including etoposide, cytosine arabinoside, cyclophosphamide, and fractionated total body irradiation. Transplantation was done in twenty-three patients with refractory leukemia. Projected survival at 917 days after transplantation in these patients is 43.4% +/- 11%. The survival of these patients so far is similar to the survival of children with acute lymphoblastic leukemia transplanted in second remission. All patients treated with this regimen who had transplantation in relapse were free of leukemia 27 days after transplantation. The results of this preliminary report suggest that an intensive preparative regimen can improve the outlook of refractory leukemia and may rescue some patients who otherwise would have died of their disease.