A database of prototypic sequences representing repetitive DNA from different eukaryotic species, together with analytical software. Repbase Update contains over 3600 annotated sequences representing different families and subfamilies. Each sequence is accompanied by a short description and references to the original contributors. Repbase Update includes Repbase Reports, an electronic journal publishing newly discovered transposable elements, and the Transposon Pub, a web-based browser of selected chromosomal maps of transposable elements.