The international ImMunoGeneTics information system® (IMGT) is a comprehensive and integrated knowledge resource created in 1989 by the Laboratoire d'ImmunoGénétique Moléculaire LIGM at Montpellier, France. It specializes in immunoglobulins (IGs), T cell receptors (TRs), major histocompatibility complex (MHC) of human and other vertebrates, and related proteins of the immune systems (RPI). IMGT includes several sequence databases, a genome database, a 3D structure database, and web resources. The data are expertly annotated according to the IMGT Scientific chart, based on the IMGT-ONTOLOGY concepts, ensuring accuracy, consistency, and integration. IMGT tools are widely used in medical research, veterinary research, biotechnology, diagnostics, and therapeutic approaches. The system is freely available at http://imgt.cines.fr.The international ImMunoGeneTics information system® (IMGT) is a comprehensive and integrated knowledge resource created in 1989 by the Laboratoire d'ImmunoGénétique Moléculaire LIGM at Montpellier, France. It specializes in immunoglobulins (IGs), T cell receptors (TRs), major histocompatibility complex (MHC) of human and other vertebrates, and related proteins of the immune systems (RPI). IMGT includes several sequence databases, a genome database, a 3D structure database, and web resources. The data are expertly annotated according to the IMGT Scientific chart, based on the IMGT-ONTOLOGY concepts, ensuring accuracy, consistency, and integration. IMGT tools are widely used in medical research, veterinary research, biotechnology, diagnostics, and therapeutic approaches. The system is freely available at http://imgt.cines.fr.