Anti-thymocyte globulin (ATG) has been used in severe aplastic anemia as a part of the conditioning regimen. Among the many kinds of ATG preparations, thymoglobulin had been found to be more effective in preventing GVHD and rejection of organ transplants. As the fludarabine based conditioning regimens without total body irradiation have been reported to be promising for BMT/PBSCT from alternative donors in SAA, thymoglobulin was added to fludarabine and cyclophosphamide conditioning to reduce GVHD and to allow good engraftment in UBMT/UPBSCT.