The reagent database dbMHC was built by the National Center for Biotechnology Information (NCBI) as an open resource for registration and characterization of HLA DNA-typing kits and reagents. Each reagent is uniquely identified as sequence-specific oligonucleotide (SSO) or primer (SSP), SSO mix, or SSP mix. Computerized prediction of allele reactivities, based on annealing stringency, is performed on all submissions to the reagent database. User-specified allele reactivities may be added or deleted independently of the prediction algorithm. Updates of allele reactivities are performed in synchronization with the IMGT/HLA database, in order to account for newly discovered alleles. Probe and primer sequences aligned to allelic sequences can be displayed at any time. Reagents registered in the reagent database are grouped in typing kits. Each kit or kit batch is uniquely identified. Group-specific amplification of alleles can be specified for an entire kit or for sections of each kit. Kits designed to test multiple loci are supported. Kits can be entered and updated via the web or submitted as batches in extensible markup language (XML) format. A tool for online interpretation of typing results is available. Both the reagent database and the typing kit database have been designed to facilitate the exchange of HLA typing based on raw typing data using the unique identifiers of kits or individual reagents. In addition, batch-wise reinterpretation of previous typing data can be performed either using the NCBI web site or by locally using downloaded allele-reactivity lists. Reinterpretation by the NCBI requires submission of raw typing data in XML format.