Over 10 million volunteer donors and cord blood units are typed for human leukocyte antigen (HLA) within hematopoietic stem cell registries and cord blood banks. Identification of matched donors in countries different from that of the searching patient is facilitated by Bone Marrow Donors Worldwide and the World Marrow Donor Association (WMDA). A survey of new volunteer donor typing among WMDA member registries has identified the methods and resolution of HLA testing and the level of quality control used to evaluate the accuracy of typing results. The diversity of HLA assignments within registries has generated a number of informatics challenges. Registries are using population genetics to enhance registry diversity and to facilitate the identification of matched donors.