SUMMARYExtracts of maize and oat plants from Sweden, infected respectively with cereal tillering disease virus and oat sterile dwarf virus, were examined in the electron microscope after staining with uranyl acetate or potassium phosphotungstate. Such extracts contained whole virus particles, two kinds of subviral particles and virus‐containing tubular structures. The results indicate that the two viruses are morphologically indistinguishable from each other and from maize rough dwarf viru