Net blotch, which is caused by the fungus Pyrenophoral teres Drechs. f. teres Smedeg., presents a serious problem for barley production worldwide, and the identification and deployment of sources of resistance to it are key objectives for many breeders. Here, we report the identification of a major resistance gene, accounting for 65% of the response variation, in a cross between the resistant line C19819 and the susceptible cv. Rolfi. The resistance gene was mapped to chromosome 6H with the aid of two recently developed systems of retrotransposon-based molecular markers, REMAP and IRAP. A total of 239 BARE-1 and Sukkula retrotransposon markers were mapped in the cross, and the 30-cM segment containing the locus with significant resistance effect contained 26 of the markers. The type and local density of the markers should facilitate future map-based cloning of the resistance gene as well as manipulation of the resistance through backcross breeding.