A seed–transmitted virus has consistently caused significant economic damage to barley crops in Korea in recent years, and may be increasing because many farmers save seed for replanting. Because some barley seed is imported, there is the potential for introduction of new seed–transmitted viruses, causing diseases which may spread. Barley cultivation in South Korea is expanding nationwide due to the increasing popularity of health foods, so both production and quality of barley grain is important. Although Barley stripe mosaic virus (BSMV) has been reported previously as a small percentage of all barley viruses present in Korea, increases in imports of barley seed may lead to increased occurrence of this seed–transmitted virus. We therefore investigated the virus status of barley crops around Iksan and Wanju. On several newly cultivated barley farms, we observed areas showing symptoms typical of BSMV, and confirmed BSMV infection in 24% of the samples examined. In order to understand the occurrence and seed transmission of Korean BSMV isolates, we examined sequence variation within the Triple Gene Block proteins, and subcellular localization of two of these proteins. The newly identified Korean BSMV isolates show low sequence variability and high sequence homology to previously reported US isolates. With these results, we expect to confirm distribution of barley viruses and possible emerging viruses, which will serve as base line data to document virus prevention and control measures.