Over 1800 mammalian miRNAs are found within RNAdb. These sequences were obtained from the latest release of miRBase (release 8.2, July 2006) (Griffiths-Jones et al., 2006). miRBase is the central repository for miRNA data on the web and is regularly maintained. We have elected to directly link the RNAdb miRNA entries to miRBase, so as to keep abreast with the most recent annotations and updates.