Immunohistochemical detection of keratin proteins in duct‐ligated submandibular glands (SMG) was carried out in mice and rats with or without testosterone administration. Keratin staining in normal salivary glands was limited to the striated duct (SD) and excretory duct (ED) cells and was usually lacking in granular convoluted tubule (GCT) cells. Following duct‐ligation, the epithelia of intercalated ducts (ICD), degranulated tubules, duct‐like structures, and dilated striated and excretory ducts showed positive keratin staining, usually in their luminal aspects. The concentration of keratin was proportional to the degree of degranulation of the GCT cells. The duct‐ligated SMGs in animals with testosterone treatment showed a comparatively higher number of granules located in the GCT cells, and degranulation was slight. Keratin staining in hormone‐treated duct‐ligated glands also occurred in ductal segments to a slight degree. Keratin was also detected in degranulated tubules, and its concentration was increased in duct‐like structures, whereas staining for EGF and NGF was decreased in degranulated tubules and lacking in duct‐