Through restriction enzyme digestion of 1,784 cosmid DNAs derived from human chromosome region Xq24→qter, we identified 353 NotI-linking cosmids (11 individual groups of overlapping NotI-linking cosmids at Xq24→q25, 6groupsatXq26→q27, and 19 groups at Xq28). Sixty-two of the 353 clones (DXS607-DXS668) contained multiple rare-cutter sites, including multiple Sacll sites within a 2-kb region, as well as one to six sites for BssHll, MluI, NotI, or NruI.