Light microscope used in histopathological investigation of Phomopsis viticola Sacc. on artificially inoculated grapevine shoots cv. Thompson seedless (highly susceptible) revealed the investigated sections immediately after inoculation, exhibited similar structure in both inoculated and non-inoculated shoots. Seven days after inoculation, Phomopsis vitico/a induced disorganized epidermal and cortical cells with a dark brown color. Fungal hyphae were clearly noticed 14 days after inoculation in both xylem parenchyma and xylem vessels causing necrosis in this tissues. Not only the pathogenic fungus caused necrosis in xylem parenchyma and xylem vessels but also colonized the tissues with their hyphae and dark inclusion bodies as well as abundant production of tylosis were clearly noticed. Twenty one days after inoculation, all tested shoot tissues were colonized with fungus hyphae causing completely break down.