Nineteen children (median age, 13 years; range 4 to 18 years) with acute lymphoblastic leukemia/lymphoma (ALL) (10 patients) or acute nonlymphoblastic leukemia (ANNL) (9 patients) received allogeneic bone marrow transplants (BMT). Marrow was taken from HLA-identical sibling donors (16 patients) (pts), HLA-identical unrelated donor (1 pt), or one-antigen-missmatched sibling donor (1 pt). Preparatory regimen consisted of fractionated total body irradiation and high-dose VP-16 (50-70 mg/kg body weight). At the time of BMT nine of the pts were not in complete remission (CR): seven pts were refractory to aggressive multiagent chemotherapy and two pts were in first relapse. Six pts were in second CR, one pt in third CR; three pts grafted in first CR carried additional risk factors; e.g. induction failure. Ten out of the nineteen pts are alive and free of disease between one and 53 months (median, 28 months) after BMT. The actuarial disease-free survival rate is 37% for pts with ANLL and 54% for pts with ALL. Six pts have died from BMT-related complications. Only three pts (1 pt with ALL, 2 pts with ANLL) have relapsed between day +106 and day +134 after BMT and subsequently died. The four-year actuarial relapse rates of 29% for ANLL and 14% for ALL, respectively, demonstrate that the combination of fractionated total body irradiation and high-dose VP-16 is an effective antileucemic regimen for children with advanced leukemias.