In Children's Cancer Group (CCG) study 2891, patients who were recently diagnosed with acute myelocytic leukemia (AML) were assigned randomly to standard- or intensive-timing induction chemotherapy. Patients in first complete remission (CR1) and who had a human leukocyte antigen (HLA)-identical, related donor or a donor disparate at a single class I or II locus were nonrandomly assigned to receive a bone marrow transplant (BMT) by using oral busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg). Methotrexate only was given for graft-versus-host disease (GVHD) prophylaxis. One hundred fifty patients received transplants. Grade 3 or 4 acute GVHD occurred in 9% of patients. Patients younger than 10 years had a lower incidence of grade 3 or 4 GVHD (4.6%) compared with patients 10 years or older (17.4%) (P =.044). Disease-free survival (DFS) at 6 years was 67% and 42% for recipients of intensive- and standard-timing induction therapies, respectively. Multivariate analysis showed that receiving intensive-timing induction therapy (P =.027) and having no hepatomegaly at diagnosis (P =.009) was associated with favorable DFS, and grades 3 and 4 acute GVHD were associated with inferior DFS. Multivariate analysis showed that grades 1 or 2 GVHD (P =.008) and no hepatomegaly at diagnosis (P =.014) were associated with improved relapse-free survival (RFS). Our results show that children older than 10 years are at higher risk for developing severe GVHD; acute GVHD is associated with favorable RFS.