Annotation and database system of full-length cDNA sequences was developed. As the components of the system, ORF annotation system, functional annotation system based on database search results, mapping annotation system, and integrated retrieval and display system were developed. In the ORF annotation system integrated analyses using conventional tools are performed and useful retrieval interface using motif list are introduced. In the functional annotation system based on database search results, a new method that characterizes a given unknown cDNA was developed by using a profile of similarity level over words appearing in sequence database entries. In the mapping annotation system, we linked by similarity searches full-length cDNA sequences with database DNA sequences that are already mapped on chromosomes. By using these links, full-length cDNAs can be retrieved by the retrieval condition of physical mapping information. Genetic disease information mapped on the physical mapping site can also be displayed by this system. Furthermore, we constructed an integrated database system for these analyzed data, and thus enabled annotation and selection of full-length cDNAs from points of both gene function and mapping information.