HLA compatibility is considered the key criterion for selecting donors for allo-HSCT. DKMS study data presented at the DGHO Annual Meeting 2025 in Cologne indicate the biological age of donors has a greater influence on transplant success than previously assumed [1]. “Our results show that we need to reevaluate the established standard for donor selection,” says Prof. Dr. Johannes Schetelig, Head of Stem Cell Transplantation Unit at the University Hospital Carl Gustav Carus Dresden and Director Clinical Research at DKMS. The international non-profit supports people with blood cancer and promotes research. Its campaigns encourage young people aged 17+ to register as stem cell donors.