Bone marrow transplantation was performed with a conditioning regimen including antithymocyte globulin (ATG) for 8 patients with HLA-compatible unrelated donors or HLA mismatched donor. Administration of ATG was halted due to side effects in only 1 case, but the other cases were had no adverse reaction. During administration of ATG, platelet counts did not decrease rapidly, but platelet infusion was not effective in some cases. As compared between patients with conventional allogeneic BMT, autologous BMT or peripheral blood stem cell transplantation and those with ATG administration, no obvious difference was seen between the two groups in lymphocyte counts, CD3, CD4, CD8 and CD20 positive cells. No patient with ATG saffered graft failure or acute GVHD. However, cytomegalovirus infection was observed more frequently than in patients without ATG. In hematological malignancy, relapse was more frequent than in patients without ATG.