The Human Gene Mutation Database (HGMD) constitutes a comprehensive core collection of data on germ‐line mutations in nuclear genes underlying or associated with human inherited disease (www.hgmd.org). Data catalogued includes: single base‐pair substitutions in coding, regulatory and splicing‐relevant regions; micro‐deletions and micro‐insertions; indels; triplet repeat expansions as well as gross deletions; insertions; duplications; and complex rearrangements. Each mutation is entered into HGMD only once in order to avoid confusion between recurrent and identical‐by‐descent lesions. By March 2003, the database contained in excess of 39,415 different lesions detected in 1,516 different nuclear genes, with new entries currently accumulating at a rate exceeding 5,000 per annum. Since its inception, HGMD has been expanded to include cDNA reference sequences for more than 87% of listed genes, splice junction sequences, disease‐associated and functional polymorphisms, as well as links to data present in publicly available online locus‐specific mutation databases. Although HGMD has recently entered into a licensing agreement with Celera Genomics (Rockville, MD), mutation data will continue to be made freely available via the Internet. Hum Mutat 21:577–581, 2003. © 2003 Wiley‐Liss, Inc.