The adult male reproductive system of Achroia grisella consists of paired testes in a common oval sheath, paired deferent ducts, accessory glands, seminal vesicles and a single ejaculatory duct. In this work, we used light and transmission electron microscopy to study the morphology of the male reproductive accessory glands of A. grisellla. The accessory gland consisted of glandular cells with a well-developed rough endoplasmic reticulum and Golgi apparatus, although no secretion was seen in the cells. Histochemical analysis showed that the accessory gland secretion consisted of glycoproteins. The variable morphological appearance of the secretion (globular, amorphous and fibrillar) present in the gland lumen and its staining properties, which changed along the gland tract, suggested that the secretion underwent some form of processing that was possibly associated with its maturation before release from the gland. We suggest that the accessory gland secretion may have a role in the maintenance of spermatozoa and/or in plug formation, as already reported for other lepidopteran species.