The ultrastructural alteration of maize plants infected with the maize rough dwarf virus (MRDV) was studied with transmission electron microscopy. The results revealed that aggregates of virus particles , with a diameter of 60nm, were found in the root cell, and always distributed near the vacuole membrane. However, no such particles were checked in leaf cells. Moreover, no virus was observed in choroplasts, mitochondria nuclei, plasmodesmata or intercellular canal of all kinds of infected cells of maize, either. Structures of various organelles changed in the infected leaf and root cells of maize. An inward collapse and localized splitting of the tonoplast were observed, the chloropoast structure was destroyed by MRDV, and the number of destroyed or dysplasia chloroplast in leaf cells with serious symptoms was more than that in leaves without symptoms. The matrix of mitochondria in cells infected by MRDV decreased and some of them expanded and destructed. Nuclei was abnormal and the nuclear membrane wa The ultrastructural alteration of maize plants infected with the maize rough dwarf virus (MRDV) was studied with transmission electron microscopy. The results revealed that aggregates of virus particles, with a diameter of 60nm, were found in the root cell, and always distributed near the However, no such particles were checked in leaf cells. Moreover, no virus was observed in choroplasts, mitochondria nuclei, plasmodesmata or intercellular canal of all kinds of infected cells of maize, either. Structures of various organelles changed in the infected leaf and inward cell of maize. An inward collapse and localized splitting of tonoplast were observed, the chloropoast structure was destroyed by MRDV, and the number of destroyed or dysplasia chloroplast in leaf cells with serious symptoms was more than that in leaves without symptoms. The matrix of mitochondria in cells infected by MRDV decreased and some of them expanded and destructed. Nuclei was abnormal and the n uclear membrane wa