We have organized the DNA sequences of Bacillus subtilis from the EMBL collection to build the NRSub data base. This data base Is free from duplications and all detected overlapping sequences are merged Into contigs. Data on gene mapping and codon usage are also included. NRSub is publically available through anonymous FTP In flat file format or structured on the form of an ACNUC data base. Under this format, It is possible to use NRSub with the retrieval program Query—win. This program integrates a graphical interface and may be installed on any kind of UNIX computer under X Window and on which the Vibrant and Motif libraries are available.