A virus isolated from soybean showing mosaic and stunting symptoms collected at Nakhorn Sawan, Northern Thailand in 1979, was identified as peanut mottle virus based on host range, symptomatology, aphid transmissibility, particle morphology, serological relationships, etc. The virus infected 15 plant species belonging to five families including systemic infection in peanut, pea, broad bean, etc., and also produced local lesions on inoculated leaves of Top Crop bean. The virus consisted of filamentous flexuous particles about 780 nm in length, and the thermal inactivation point, dilution end point, and longevity in vitro of the virus were 55 - 60 °C for 10 min, 10^-3-10^-4, and 7-14 days at 20°C, respectively. In ultrathin sections, pinwheel and bundle type inclusion bodies were observed in the cytoplasm. The virus reacted positively with antiserum to the Japanese isolate of peanut mottle virus.