At the request of the IT Working Group of the World Marrow Donor Association (WMDA), we are making a number of computer readable files available. These files will document: the official WHO HLA Nomenclature, the relationships between serologically defined antigens and the relationships between HLA allele sequences and their serologically defined antigens. Updated versions of these files will be released every three months at the time new versions of the IMGT/HLA Database become available.