Immunohistochemical study of expression of calmodulin, S-100 α, β protein and cytokeratin K8.12 was carried out on normal and duct-ligated submandibular (SMG) and sublingual glands (SLG) of rats. The normal rat SMG showed calmodulin and S-100 α immunoreactivity in the pillar and transition cells of the granular convoluted tubule (GCT) and striated duct cells. S-100 β staining was positive in acinar cells of SMG as fine granular deposition. A trace immunoreaction product of keratin K8.12 was observed in GCT segments and striated ducts. Three days following duct ligation, immunostaining for calmodulin and S-100 β disappeared in both SMG and SLG, however, S-100 α staining persisted in pillar, transition and striated duct cells. The altered GCT cells of SMG and duct-like structures of SLG in the duct-ligated glands also showed S-100 α staining. In addition, K8.12 immunoreactivity was noted in the duct-like structures, particularly in those cells located luminally. The day 5 duct-ligated specimen of SMG retained positive S-100 α protein in the newly formed duct-like structures and the day 7, 10 and 14 specimens showed squamous metaplasia with positive K8.12 staining at the luminal side of the ducts. Myoepithelial cells in duct-ligated SLG stained positively for K8.12. It is concluded that loss of calmodulin from the ductal cells of SMG and SLG, and S-100 β from acini of SMG marks the earliest and predominant pathological alteration followed by increased proliferation of duct-like structures with cells containing cytokeratin K8.12 as pathological alteration of duct ligation of the salivary glands.