The technology of sequencing expressed sequence tags (ESTs) offers a relatively cheap alternative to whole genome sequencing and has become a valuable resource for gene discovery. The inherent characteristics of ESTs, such as transcript redundancy, low sequence quality and high error rates, require processing of the sequences before any gene prediction can be made. The process includes EST pre-processing, analysis and similarity searches, and the data are generally stored in a database to organise the results and thereby assist the search for interesting genes.