Three-week-old tamarillo seedlings were inoculated on the cotyledons and first true leaf with seven different viruses known to infect solanaceous plants. Five of the viruses caused systemic mosaic or necrotic symptoms in some or all of the inoculated plants. Alfalfa mosaic, cucumber mosaic and tomato spotted wilt viruses were the most severe, causing significant decreases in leaf, stem and root dry weight. Tobacco streak virus caused a significant decrease in dry weight of roots only, but results with potato virus X were not significant. Potato virus Y and tobacco mosaic virus failed to cause infection in tamarillo as indicated by lack of symptoms, failure to recover virus in indicator plants and failure to detect virus particles in leaf extracts using immunosorbent electron microscopy.