RATIONALE: Bone marrow transplantation may be able to replace immune cells that were destroyed by chemotherapy used to kill tumor cells. Sometimes the transplanted cells can make an immune response against normal tissues. Methotrexate and cyclosporine may prevent this from happening.

PURPOSE: Phase III trial to study the effectiveness of treatment with methotrexate and cyclosporine after bone marrow transplantation to provide protection against acute graft-versus-host disease.

OBJECTIVES: I. Determine the efficacy of a combination of methotrexate and cyclosporine, administered after grafting, to prevent the development of acute graft versus host disease (GVHD) in patients undergoing allogeneic bone marrow transplantation.

OUTLINE: Patients receive methotrexate IV on days 1,3,6, and 11. Patients also receive cyclosporine IV twice a day until the patient is eating, then it is administered orally twice a day. Cyclosporine begins on day -1 and continues until day 180. The dose is reduced beginning on day 50.

PROJECTED ACCRUAL: Accrual will continue until further notice.

DISEASE CHARACTERISTICS: Ongoing bone marrow transplantation from HLA-matched siblings or HLA non-identical family members or unrelated donor

PATIENT CHARACTERISTICS: Age: Any age Performance status: Not specified Life expectancy: Not severely limited by disease other than leukemia Hematopoietic: Not specified Hepatic: No severe hepatic disease Renal: No history of hemorrhagic cystitis No renal disease Cardiovascular No symptomatic cardiac disease Other: No contraindication to the use of cyclosporine or methotrexate

PRIOR CONCURRENT THERAPY: No concurrent experimental treatment on other GVHD prophylaxis studies