This project deals with seven important areas of allogeneic bone marrow transplantation for hematologic malignancy: 1. We propose to conduct a prospective collaborative trial comparing high dose chemoradiotherapy and marrow transplantation to chemotherapy for patients with acute lymphoblastic leukemia during first complete remission. 2. We will perform a phase II study to decrease the relapse rate in patients with leukemia by the addition of cyclophosphamide to the combination of FTBI and VP-16 (acute non-lymphoblastic leukemia (ANLL) in first complete remission, chronic myelogenous leukemia (CML) in chronic phase, acute lymphoblastic leukemia (ALL) and acute non-lymphocyte leukemia not in first remission, chronic myelogenous leukemia not in chronic phase). 3. We will explore the effectiveness of a new preparatory regimen of FTBI, VP-16 and cyclophosphamide in patients receiving matched unrelated transplants or partially matched related transplants. 4. We will also study methods of preventing cytomegalovirus pneumonia by altering the natural history of HCMV infection after allogeneic bone marrow transplantation. 5. We will determine the effectiveness of a new anti-graft-versus-host disease regimen of cyclosporin, prednisone and xomazyme in patients receiving bone marrow allografts from partially matched unrelated or related donors. 6. We will determine the role of thalidomide in the prevention of chronic graft-versus-host disease after allogeneic bone marrow transplantation. 7. We will conduct a randomized trial to determine the efficacy of methotrexate, cyclosporin and prednisone compared to xomazyme, cyclosporin and prednisone for patients receiving matched sibling allografts.