982 progeny produced by a mouse interspecific backcross between C57BL/6 and Mus spretus have been scored for at least 3 markers on each chromosome, completing an anchor map of 78 loci across the mouse genome. The anchor mapping identifies all the available recombinants in each interanchor interval allowing access to panels of mice that can be used for the high resolution mapping of any chromosome region. The large number of progeny recovered and scored from the interspecific backcross allows us to resolve genetically markers that lie on average 200 kb apart on mouse chromosomes and within the cloning capacity of currently available YAC libraries. EUCIB provides the first genetic mapping resource specifically designed for the high resolution mapping of all regions of the mouse genome and will underpin the global physical mapping of the mouse genome. In addition, with the use of conserved sequences the facility is applicable to the high resolution comparative mapping of the mouse and human genomes. A new database has been implemented to support the computation of high resolution and ordered genetic maps.