IMGT, the International ImMunoGeneTics information system ( http://imgt.cines.fr ), was created in 1989 by the Laboratoire d'ImmunoGénétique Moléculaire (LIGM) (Université Montpellier 2 and CNRS) at Montpellier, France, in order to standardize and manage the complexity of immunogenetics data. IMGT is recognized as the international reference in immunogenetics and immunoinformatics. IMGT is a high quality integrated knowledge resource, specialized in (i) the immunoglobulins (IG), T cell receptors (TR), major histocompatibility complex (MHC) of human and other vertebrates; (ii) proteins that belong to the immunoglobulin superfamily (IgSF) and to the MHC superfamily (MhcSF); and (iii) related proteins of the immune systems (RPI) of any species. IMGT provides a common access to standardized data from genome, proteome, genetics, and three-dimensional (3D) structures for the IG, TR, MHC, IgSF, MhcSF, and RPI. IMGT interactive on-line tools are provided for genome, sequence, and 3D structure analysis. IMGT Web resources comprise 10,000 HTML pages of synthesis and knowledge (IMGT Scientific chart, IMGT Repertoire, IMGT Education, etc.) and external links (IMGT Bloc-notes and IMGT other accesses).