‘Nomenclature of the Human Immunoglobulin Lambda (IGL) Genes’, the 18th report of the ‘IMGT Locus in Focus’ section, provides the first complete list of all the human IGL genes. The total number of human IGL genes per haploid genome is 87–96 (93–102 if the orphons are included), of which 37–43 genes are functional. IMGT/Human Genome Organization (HUGO) gene names and definitions of the human IGL genes on chromosome 22q11.2 and IGL orphons on chromosomes 8 and 22 are provided with the gene functionality and the number of alleles, according to the rules of the IMGT Scientific chart, with the accession numbers of the IMGT reference sequences and with the accession ID of the Genome Database GDB and NCBI LocusLink databases, in which all the IMGT human IGL genes have been entered. The tables are available at the <b>IMGT</b> Marie-Paule page of IMGT, the international ImMunoGeneTics database <b>(http://imgt.cines.fr)</b> created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France.