IMGT, the international ImMunoGeneTics database (http:/(/)imgt.cnusc.fr:8104) is an integrated database specialising in immunoglobulins (Ig), T-cell receptors (TcR) and major histocompatibility complex (MHC) of all vertebrate species, created by Marie-Paule Lefranc, CNRS, Montpellier II University, Montpellier, France (lefranc@ligm.crbm.cnrs-mop.fr). IMGT includes three databases: LIGM-DB for Ig and TcR, MHC/HLA-DB, and PRIMER-DB (the last two in development). The new section of Experimental and Clinical Immunogenetics, 'IMGT locus on focus', will give the more updated and extensive overview of the current status of the different Ig, TcR and MHC genes in IMGT, with standardization of gene nomenclature, functionality, and allele polymorphism according to the IMGT rules and unique numbering.