Three human chromosome 2-specific clone libraries were constructed and characterized. Chromosome 2-specific cosmid and fosmid clone libraries were constructed using flow-sorted DNA from the monochromosomal hybrid cell line GM10826. The cosmid and fosmid libraries consist of 38,496 and 26,400 arrayed clones, respectively, with an average size of 40 kb. Colony hybridization of a representative number of clones with both human and hamster genomic DNA probes demonstrates that between 58 and 66% of the clones in the flow-sorted libraries contain human inserts. Approximately 5% of the cosmid and fosmid clones are nonrecombinants. A chromosome 2-specific PAC library was also produced from the hybrid cell line GM10826. DNA from the hybrid cell line was cloned, and the human chromosome 2-specific clones were identified by colony hybridization. Approximately 5800 chromosome 2-specific PAC clones with an average insert size of approximately 85 kb were arrayed. Based on the size of the clones, the cosmid, fosmid, and PAC libraries are approximately 3.6x, approximately 2.5x, and approximately 1.9x, respectively in chromosomal coverage. The chromosome 2 coverage of each of the three libraries was further determined by PCR screening clone pools with 82 chromosome 2-specific STSs. The average number of clones identified for each STS in the library indicates the cosmid, fosmid, and PAC libraries to be approximately 3.2x, approximately 2.1x, and approximately 1.5x, respectively, in chromosome coverage. All except one of the 82 STSs were represented in the portions of the libraries screened.