Resistance Gene Analogs (RGA) in plants are related to the NBS-LRR class of disease resistance genes which are characterized by Nucleotide Binding Site (NBS) and Leucine Rich Repeat (LRR) regions. The NBS, in particular, contains several sequence motifs which are highly conserved among disease resistance genes and RGA from distantly related plants, thus facilitating their use for the isolation of new RGA and perhaps actual disease resistance genes. To isolate RGA from barley, we screened a 6X barley BAC (bacterial artificial chromosome) library using - ³²P-ATP labeled synthetic DNA primers complementary to the conserved motifs of NBS as hybridization probes.Two BAC clones, out of 59 positives, contained RGA related sequences. These were subcloned, sequenced, and two RGA probes, designated RSB001 and ABG331 were identified. The RSB001 probe identified a small gene family mapping to loci on chromosomes 1,2, and 7 and possibly other, yet undetermined, loci. The ABG331 probe mapped to three loci on chromosome 1 and one on chromosome 7. The RGA probes were used to identify BAC clones corresponding to the mapped loci and additional RGA subclones obtained and analyzed by sequencing. This approach allowed us to identify new, previously undescribed, RGAs from barley.