In order to facilitate the cloning of agronomically important genes in barley, a bacterial artificial chromosome (BAC) library for the cultivar Morex was constructed. The library contains 313, 344 clones (816 - 384-well plates). A random sampling of 500 clones indicated an average insert size of 106 kbp (range = 30 to 195 kbp), 3.4% empty vectors, and 1.5% contamination with chloroplast DNA. Thus, the library provides 6.3 haploid genome equivalents allowing >99% probability of recovering any specific sequence of interest. High-density filters were gridded robotically using a Genetix Q-BOT in a 4x4 double-spotted array on 22.5 cm² filters. The library has been used to identify BAC clones for numerous probes by several investigators. We screened the library with 40 single copy probes. These probes yielded an average of 6.4 clones per probe with a range of 1 -13. The barley resistance gene analog (RGA) probe ABG331 identified 36 BAC clones representing at least 4 loci and a maize RGA probe, Pic20, identified 65 BAC clones representing one complex and 2 other loci. The Leister B2-B9 probes yielded approximately 100 clones with an average of 12.5 clones per probe. Additional searches with the rice Xa21 and the wheat LRK probe produced 31 and 10 clones, respectively. These data clearly indicate a very robust library. Applications of the library to gene isolation and physical mapping in barley will be discussed.