OUTLINE: This is a randomized, multicenter study. Patients are stratified according to age (15-39 vs 40-65), interval from diagnosis to transplantation (under 2 years vs 2 years or more, and permutations of patient and donor gender. Patients are randomized to one of two treatment arms. Arm I: Patients receive a preparative regimen comprising busulfan orally or IV 4 times daily on days -7 to -4 and cyclophosphamide IV on days -3 and -2. Allogeneic filgrastim (G-CSF)-mobilized peripheral blood stem cells are infused on day 0. Arm II: Busulfan and cyclophosphamide are administered as in arm I. Allogeneic bone marrow is infused on day 0. Patients receive graft-versus-host disease prophylaxis comprising methotrexate IV on days 1, 3, 6, and 11 and cyclosporine IV over 1-4 hours or orally every 12 hours on days -1 to 80 and then tapered. Patients are followed every 6 months for 2 years and then annually thereafter.