A virus was isolated from soybean plants showing yellow vein symptoms that were collected in the central part of Thailand in 1982. The virus was a new virus of soybean based on particle morphology, host range, stability in crude sap, etc. It was designated as soybean yellow vein virus (SYVV). The occurrence and distribution of SYVV disease were limited. Numerous rod-shaped virus particles (about 500-550 nm in length and 15-20 nm in width) were detected in the dip preparations of soybean leaves infected with the virus. Chenopodium amaranticolor and C. quinoa showed chlorotic local lesions on the inoculated leaves and only soybean was recognized as a systemic infectious host of the virus showing yellow vein symptoms. Aphis glycinesand Bemisia tabaci failed to transmit the virus. The dilution end point, thermal inactivation point and longevity in vitro of the virus were 10^-3 -10^-4, 35-40°C (10 min) and 2-3 hr at 4°C, respectively.