The ultrastructure of accessory genital glands in Raillietiella sp. is described and their function is discussed. In females we assume that they reactivate sperm, which are stored in the receptacula seminis after copulation. In males we think they are primer-pheromone glands, which inject secretions into the female during copulation and stimulate the development of the female genital system. This study presents a revised nomenclature, which allows for the comparison of former results.