INTRODUCTIONSince the creation of IMGT, the international ImMunoGeneTics information system in 1989, at New Haven during the 10th Human Genome Mapping Workshop (HGM10), the standardized classification and nomenclature of the immunoglobulins (IG) and T cell receptors (TR) of human and other vertebrate species have been under the responsibility of the IMGT Nomenclature Committee (IMGT-NC). In 1995, following the first demonstration online of the nucleotide database IMGT/LIGM-DB at the 9th International Congress of Immunology in San Francisco, IMGT-NC has become the World Health Organization-International Union of Immunological Societies (WHO-IUIS)/IMGT Nomenclature Subcommittee for IG and TR. As described here, IMGT gene and allele names are based on the concepts of classification of “Group,” “Subgroup,” “Gene,” and “Allele,” generated from the IMGT-ONTOLOGY CLASSIFICATION axiom. The IMGT gene nomenclature for IG and TR genes was approved at the international level by the Human Genome Organisation (HUGO) Nomenclature Committee (HGNC) in 1999 and by the WHO-IUIS. The IMGT IG and TR gene names are the official reference for the vertebrate genome projects and, as such, have been entered in IMGT/GENE-DB, the IMGT gene database, in Entrez Gene (National Center for Biotechnology Information [NCBI]), in Ensembl (European Bioinformatics Institute [EBI]), and in the Vega Genome Browser (Wellcome Trust Sanger Institute).