Considering the merit and demerit of GVHD in leukemia patients following allogeneic BMT, our strategies for GVHD are as follows; (1) a mild prevention, (2) a treatment to control the severity, if occurred, and (3) an induction of GVHD in recipients who did not develop GVHD. We reported the results of recent trials in prevention, treatment and induction of GVHD. For the prevention, T cells were depleted from bone marrow cells in 11 recipients with the results of graft failure in 5 and death in 9. The data from IBMTR were similar to our data. For the treatment, new drugs, 15-Deoxyspergualin. Mizoribine and anti-human lymphocyte globulin were introduced with compromising outcomes and mild adverse effects. For the induction, Ubenimex, an immunostimulator, was administered to recipients who did not develop GVHD until 30 days after BMT. The interim data suggests that Ubenimex may induce chronic GVHD and suppress the relapse of leukemia. We experienced the sudden onset of GVHD during the tapering of immunosuppressants in two recipients, who were found to have arbitrarily discontinued them. The interruption of drugs for the prevention of GVHD may cause the induction of GVHD.