Progressive pulmonary sarcoidosis occurs in up to twenty percent of patients who require persistent treatment, but available treatment options have shown considerable long-term toxicity and uncertain or unproven efficacy. In these patients, pulmonary fibrosis and pulmonary hypertension are common complications which have major prognostic impact. Endothelin-1 (ET-1) has been demonstrated to play a key role in pulmonary fibrosis and pulmonary hypertension, and a potential role in pulmonary sarcoidosis. ET-1 is a potent vasoconstrictor and can promote fibrosis, cell proliferation, and remodeling, and is pro-inflammatory. Preliminary data have shown the therapeutic potential of the endothelin receptor antagonist (ERA) bosentan in sarcoidosis associated pulmonary hypertension.