OBJECTIVES: I. Compare the efficacy of a busulfan containing conditioning regimen versus a total body irradiation (TBI) containing regimen for children with acute lymphoblastic leukemia (ALL) undergoing allogeneic bone marrow transplantation. II. Compare relapse rate between a chemotherapy only regimen versus a total body irradiation containing regimen for children with ALL. III. Assess and compare the acute and chronic neuropsychological effects of bone marrow transplantation (BMT) in children undergoing BMT with busulfan or TBI conditioning regimens. IV. Assess and compare the cardiac, pulmonary and growth effects of BMT in children undergoing this conditioning regimen. V. Assess the relationship between plasma busulfan levels and relapse and toxicity. VI. Assess and compare minimal residual disease patterns by quantitative polymerase chain reaction (PCR) in patients receiving busulfan or TBI conditioning regimens.