The cyclic changes of the epithelium of seminiferous tubule in the Korean greater horseshoe bat (Rhinolophus ferrumequinum korai) were investigated by means of the light and electron microscopic observations and the following results were obtained. 1) The spermatogenic function of the horseshoe bats captured in September was moderate but considerable amount of the ultrastructural findings were obtained in both the spermatocytogenic and the spermiogenic phases. 2) The spermatogenic function of the horseshoe bats captured in December was depressed representing a resting status. 3) The light and electron microscopic findings suggest that the epithelium of seminiferous tubule varies cyclically, which is closely related to their peculiar way of reproductive habit during hibernation.