Histopathology of Karnal bunt infected wheat was investigated using light microscopy. Susceptible wheat plants were inoculated by Goates" and Injection methods. During the early stages of infection, in the plants inoculated by Goates" method, hyphae were present intercellularly in the distal to midportions, but not basal portions of the glume and lemma, and were absent in the ovary, funiculus and rachis. In the plants which were inoculated by injection method, during the early stages of infection, intercellular hyphae were present in all portions of glume, lemma, and rachis, but not observed in the ovay and funiculus. Hyphae were seen In funiculus at a later stage. In all observations, it appeared that hyphae from different parts of spike grew toward the basal parts of florets ana entered to ovary through funiculus. Ten days after inoculation, developing teliospores were observed in the pericarp of the caryopsis, and 13 days after inoculation, mature teliospores with thick exosporium wall were developed.