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Abstract Tomato Ring Spot Nepovirus (ToRSV) is one of the most serious viruses affecting grapevine, tomato and other hosts. The virus is distributed in most parts of the world and found in herbaceous, ornamental and woody species including tomato, tobacco, grape, apple, peach, cherry, apricot and raspberry. The virus was isolated from infected grapevine which was characterized by ring spots, mottling and shortening of internodes. And from tomato exhibiting necrotic rings and sinuous lines symptoms. Eleven plant species and cvs. belonging to 6 families were infected by ToRSV while 6 others belonging to 4 families didn’t show symptoms and gave negative results with DAS-ELISA. Virus particles were detected as isometric particles with TEM of about 28nm. Anatomical and ultrastructure changes in leaf tissues of both Tomato and Grapevine artificially infected with Tomato Ring Spot Nepovirus were studied by light and electron microscopy. By light microscopy viral infection resulted in the presence of amorphous inclusion bodies in the cytoplasm of infected leaves. Phloem tissues were also affected by infection. Investigations of leaf tissues of both tomato and grapevine by Transmission Electron Microscope (TEM) revealed several ultrastructure changes in each of chloroplast, mitochondria, and the nucleus. The ultrastructure changes expanded also to the cell wall, cell membrane and the endoplasmic reticulum. The chloroplast exhibited different degrees of malformation and laysis |