Adult and developing salivary glands were investigated using five monoclonal antibodies against cytokeratins (CKs) and vimentin. Acinar cells displayed mainly CK 18 whereas CKs 7, 17 and 19 were only detected in duct and myoepithelial cells. All epithelial and myoepithelial cells were unreactive for one vimentin antibody (Vim 9) whereas with the other (Vim 24), myoepithelial cells and basal cells of excretory ducts were stained. Fetal cells showed the CK pattern of duct cells. At gestational week 18, a reaction for both vimentin antibodies could be found in basal cells of terminal tubules. Although vim 9 reactivity has been shown for a number of salivary neoplasms, it has not been detected in any adult epithelial salivary tissue. The finding of this reactivity in the fetal gland indicates that the expression of this intermediate filament protein in certain salivary neoplasms may be a sign of dedifferentiation resulting in the expression of a filament pattern found in an earlier stage of gland development.