The highly polymorphic human leukocyte antigen (HLA) genes, located in the human major histocompatibility complex, encode the class I and II antigen-presenting molecules which are centrally involved in the immune response. HLA typing is used for several clinical applications such as transplantation, pharmacogenetics, and diagnosis of autoimmune disease. HLA typing is highly complex due to the homology of HLA genes and pseudogenes and the extensive polymorphism in the population. The Centers for Disease Control and Prevention (CDC) established the Genetic Testing Reference Materials Coordination Program (GeT-RM) in partnership with the genetics community to improve the availability of genomic DNA reference materials necessary to assure the quality of genetic laboratory testing. The GeT-RM together with three clinical laboratories and the Coriell Cell Repositories have characterized genomic DNA obtained from a panel of 108 cell lines for all HLA classical polymorphic loci: HLA-A, B, C, DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, DPA1, and DPB1. The goal was to develop a publicly available and renewable source of well-characterized genomic DNA reference materials to support molecular HLA typing assay development, validation, and verification, quality control, and proficiency testing. These genomic DNA samples are publicly available from the National Institutes of General Medical Science (NIGMS) Repository at the Coriell Cell Repositories.