OUTLINE: Patients with unrelated donors, mismatched related donors, or matched related donors diagnosed with acute lymphocytic leukemia, chronic lymphocytic leukemia, myeloma, or advanced acute myeloid leukemia (AML), receive cyclophosphamide IV over 60 minutes on days -6 and -5 and fractionated total body irradiation (TBI) 3 times a day on days -3 through -1, and twice on day 0. Patients receive graft vs host disease (GVHD) prophylaxis with anti-thymocyte globulin (ATG) IV over 8 hours on days -2 and -1. Patients undergo allogeneic bone marrow transplantation (ABMT) on day 0 with marrow grafts modified by T cell depletion with counterflow centrifugal elutriation and CD34+ selection. Patients unable to receive TBI due to matched or mismatched related donors, or age (56 to 60), or patients diagnosed with AML-CR1, chronic myelogenous leukemia, myelodysplastic syndrome, or myeloproliferative disorders with matched related donors, receive oral busulfan every 6 hours on days -7 through -4, cyclophosphamide IV over 60 minutes on days -3 and -2, and ATG IV over 8 hours on days -2 and -1 for GVHD prophylaxis. Patients undergo T cell depleted ABMT on day 0. At pretransplantation, patients with acute leukemia receive intrathecal (IT) methotrexate (MTX) following lumbar puncture. At 48 hours following IT MTX, patients with CNS involvement receive a second dose of IT MTX followed by oral leucovorin calcium every 6 hours for 4 doses. Patients with prior CNS involvement receive cranial radiotherapy for 2 weeks. Following AMBT, patients undergo GVHD prophylaxis consisting of methylprednisolone IV every 12 hours on days 5-22, and then once daily on days 23-28 and cyclosporine IV or orally twice daily beginning on day -1 and continuing until 7-9 months following ABMT. Patients are followed every 3 months until death.