dbMHC provides access to HLA sequences, tools to support genetic testing of HLA loci, HLA allele and haplotype frequencies of over 90 populations worldwide, as well as clinical datasets on nematopoietic stem cell transplantation, and insulin dependant diabetes mellitus (IDDM), Rheumatoid Arthritis (RA), Narcolepsy and Spondyloarthropathy. All clinical datasets housed at the dbMHC provide access to genotypic and phenotypic data on anonimyzed samples with aggregate query functions, and complete download capability.