Nearly half of the unrelated hematopoietic SCTs facilitated worldwide involves an exchange of products between countries. The process is information intensive and requires coordination through regional hubs of complex data transactions of demographic, clinical and genetic information, laboratory samples and results. Each registry has developed its own unique systems for representing data and process leading to transplantation. The WMDA Information Technology Working Group was formed in the autumn of 2001 as a forum to discuss and develop standards for information technology (IT) in support of hematopoietic stem cell registries. Its membership includes experts in IT from the WMDA member registries. The group has focused its standardization efforts on three areas: Standardized reference data sets for validation and plausibility controls for HLA and other data domains. Matching algorithm standards for determining histocompatibility. Communication standards between registries.