OUTLINE: This is a dose escalation study. Groups of 6-12 patients receive escalating doses of rapamycin until the maximum tolerated dose of rapamycin given in combination with methotrexate/cyclosporine is determined. All patients receive cyclosporine from the day prior to transplant until day 50 post-transplant; the dose is then tapered over 130 days. Methotrexate is given on days 1, 3, and 6 post-transplant. Rapamycin is given every other day, days 7-59. Bone marrow transplantation occurs on day 0. Patients may not receive concurrent therapy with agents that could interfere with rapamycin metabolism, intravenous lipids, FK506 or other immunosuppressive agents (prednisone allowed), NSAIDs, or other cytotoxic agents. Patients are followed at 6 months for 2 years, then annually.