The gene, Rpg1, conferring stable resistance in barley to the wheat stem rust pathogen (Puccinia graminis f. sp. tritici) was mapped using two doubled haploid populations. Rpg1 mapped to the extreme subteleomeric region of barley chromosome 1P 0.3 and 1.1 cM proximal from the molecular markers ABG704 and plastocyanin (Plc), respectively, and 2.2 cM distal from MWG036B. The closest marker, ABG704, was sequenced and PCR-based markers were developed.