IMGT, the international ImMunoGeneTics database is an integrated database specializing in Immunoglobulins (Ig), T-cell receptors (TcR) and MHC molecules of all vertebrate species, created by Marie-Paule Lefranc, University of Montpellier, CNRS, Montpellier, France (Nucleic Acids Research, Database issue, Vol 26, January 1998). IMGT includes three databases: LIGM-DB (for Ig and TcR), MHC/HLA-DB and IMGT/PRIMER-DB (an Ig, TcR and MHC-related primer database), the last two in development. IMGT comprises expertly annotated sequences and alignment tables. LIGM-DB contains more than 24.000 Immunoglobulin and T cell Receptor sequences from 81 different species. MHC/HLA-DB contains class I and class II Human Leucocyte Antigen alignment tables. An IMGT tool, DNAPLOT, developed for Ig, TcR and MHC sequence analysis, is also available. IMGT goals are to establish a common data access to all immunogenetics data, including nucleotide and protein sequences, oligonucleotide primers, gene maps and other genetic data of Ig, TcR and MHC molecules, from all species, and to provide a graphical user friendly data access. IMGT has important implications in medical research (repertoire in autoimmune diseases, AIDS, leukemias, lymphomas), therapeutical approaches (antibody engineering), genome diversity and genome evolution studies. In this paper, we describe our approach for the data modelisation, the automation of the annotation procedure and control of data quality in LIGM-DB database. IMGT is freely available on the CNUSC WWW server at Montpellier: http://imgt.cnusc.fr: 8104 (contact: Denys.Chaume@cnusc.fr) and on the EBI servers: http://www.ebi.ac.uk/imgt (contact: firstname.lastname@example.org) and ftp.ebi.ac.uk/pub/databases/imgt. LIGM-DB users are encouraged to report errors or suggestions to email@example.com- mop.fr. IMGT initiator and coordinator: Marie-Paule Lefranc, firstname.lastname@example.org. (fax: +33(0)467040231).