Objective: Refinements in HLA testing have resulted in improved outcomes of unrelated donor transplantation.Recently, the grouping of HLA matching for unrelated donors has been suggested, and can be categorized into well-matched,partially matched, and mismatched classifications.In this study,the role of anti-thymocyte globulin (ATG) for each group was evaluated.Methods: Data of 120 patients diagnosed with hematologic diseases and received allogeneic stem cell transplantation (SCT)from unrelated donors were retrospectively analyzed.