In leaf tissue of Phyllostachys bambsoides infected with Aciculosporium take, pathogens were recognized in inter-cellular spaces and on the surfaces of the suscept leaf sheath. Cell wall and cell membrane of the suscept cells were not invaginated by the invasion of the pathogen and haustorial structure of the pathogen was not observed in the suscept cells. Cell membrane, end oplasmic reticula, mitochondria, nucleus and nucleolus were observed clearly in the cells of the pathogens. The size of mitochondria of the fungal hyphae were smaller than those of the suscept and sometimes electron-dense substance was found in vacuoles of fungal hyphae.