Endothelin (ET), a potent vasoconstrictor and bronchoconstrictor peptide synthesized by endothelial and epithelial cells, was examined for its potential functions in human inferior turbinate nasal mucosal tissue by four techniques: (1) immunoreactive ET was localized in the mucosa by immunohistochemistry; (2) receptors for ET were identified by autoradiography employing [125I]ET; (3) ET-1 mRNA was localized by in situ hybridization; and (4) the secretory functions of ET were examined by the release of mucous and serous cell products after the addition of ET to human nasal turbinates in short-term cultures. Specific ET-1-immunoreactive material was found most extensively in small muscular arteries and in serous cells in submucosal glands. ET-1 was also found to a lower extent in the walls of venous sinusoids. [125I]ET-1 binding sites were localized by autoradiography to submucosal glands and to venous sinusoids and small muscular arterioles. mRNA for ET-1 was found most extensively in the venous sinusoids and to a lesser extent in small muscular arteries. In mucosal explant cultures, ET-1 and ET-2 stimulated lactoferrin and mucous glycoprotein release from serous and mucous cells, but ET-3 was inactive. The observations indicate that in the human nasal mucosa, ET is present in the vascular endothelium and the serous cells in submucosal glands and acts on glandular ET receptors to induce both serous and mucous cell secretion. It is also likely that ET plays a role in the regulation of vasomotor tone.