Two viruses belonging to the tomato spotted wilt virus group were isolated from peanut showing chlorosis and necrosis on young leaves. These viruses infected a wide range of host plants, and had a thermal inactivation point of 40-45°C for 10 min, dilution end point of 10-100 times, and longevity in vitro of about 2 hr at 20°C. In ultrathin sections, infected cells contained spherical particles 80-100 nm in diameter with an envelope and wrapped by endoplasmic reticulum.