Systemic virus symptoms caused by a Potexvirus were observed on leaves of infected hosta (Hosta spp.) plants cultivated in Seoul, Korea. Symptoms on diseased hosta plants include mosaic, mottle, irregular blotchy patches, and chlorotic spots on or distortion of the leaves. No other viruses, such as Cucumber mosaic virus, Lily symptomless virus, or Potyvirus, were detected from the same plants by electron microscopy and by Western blot and RT-PCR analyses, indicating that they were singly infected by the potexvirus. The symptoms differed among cultivars and species of hosta, and affected the quality of plants for commercialization, as well as, plant growth and flowering of susceptible cultivars. Most of the cultivars and species investigated were susceptible to the virus, while some were not infected by the virus at all. Purified virus particles were of filamentous type with unaggregated forms 540 nm in length, which is a typical potexviral morphology. The virus consisted of a single-stranded RNA molecule of 6 kb long for genome and single component of coat protein (CP) about 27 kDa. The CP strongly reacted with the antiserum against Hosta virus X (HVX), suggesting that the virus is an isolate of HVX. This is the first report of the occurrence and identification of HVX from hosta plants in Korea.