Studies with the transmission electron microscope were used to detect and attempt to identify viruses infecting sweetpotato (Ipomoea batatas) and other Ipomoea species. Flexuous-rods, short curved-rods, and spherical viruslike particles were observed in cells of symptomatic plants. Also, various cytopathic changes such as crystals, vesicles, fibril structures, and cylindrical inclusions were observed. The present study showed that some of these cytopathic changes were associated with some viral groups, which might be helpful in diagnosis.