Mucus hypersecretion is a feature of several respiratory diseases and frequently leads to obstruction of small airways where the principal source of mucins, the major macromolecular constituents of mucus, are goblet cells. Hence, inhibition of mucin secretion from these cells may be clinically beneficial. In this study we have developed a lectin-based assay for mucin secretion from ovine airway goblet cells and used this to investigate the regulation of these cells by endothelin-1 (ET-1). ET-1 inhibited baseline mucin secretion (maximum inhibition: 60.3±4.2%, IC₅₀: 0.8±0.17nM). This response was abolished by the ET_A antagonist, BQ-123 (1µM), but not by the ET_B antagonist, BQ-788 (1µM). ET-1 (1µM) did not affect mucin secretion stimulated by ATP (100µM) but secretion in response to ATP (10µM) was inhibited by 63.3±11.8%. This response could be eliminated by BQ-123, but not by BQ-788. Radioligand binding and immunohistochemistry indicated the expression of both ET_A and ET_B receptors on the epithelium. In summary, ET-1, acting via ET_A receptors, inhibits baseline and ATP-stimulated mucin secretion from ovine airway goblet cells. This represents the first report of a physiological mechanism for inhibiting airway goblet cell mucin secretion and understanding of this mechanism may provide opportunities for the treatment of obstructive airways disease.