MOTIVATION: To develop tools for the submission of mutations to databases and maintenance of locus-specific mutation databases. Advanced, integrated computer systems are needed to store and organize the increasing mutation information. RESULTS: The MUTbase program suite provides an easy, interactive and quality-controlled submission of information to mutation databases. For further study of the databases on the World Wide Web, a number of tools are provided. The program package also writes and updates a large number of Web pages, e.g. about the distribution and statistics of disease-causing mutations, and changes in restriction patterns.