Relatively few DNA probes have been regionally assigned to chromosome 13 bands, and these tend to be clustered in the proximal end of the chromosome in the regions where intensive mapping efforts have been focused because of the retinoblastoma and Wilson disease genes. We have developed a chromosome 13-specific half-linking library of NotI-HindIII fragments and regionally mapped 32 of these on chromosome 13, using a somatic cell hybrid panel that subdivides chromosome 13 into 11 regions and nonisotopic in situ hybridization with silver amplification of a digoxigenin-labeled probe.