OBJECTIVES: I. Estimate the maximum tolerated dose of rapamycin that can be safely combined with standard methotrexate/cyclosporine prophylaxis for graft-versus-host disease (GVHD) in patients with hematologic disorders who have received a bone marrow transplant from a related donor who is mismatched for 1 HLA-A, -B, or -DR antigen in the GVHD direction.