Pulmonary arterial hypertension(PAH) is an uncommon disease characterised by a progressive increase in pulmonary vascular resistance. An imbalance between vasoconstrictor/vasodilator activities could be responsible for altered pulmonary vascular tone and structure. In PAH patients, endothelin are increased. Restoration of this imbalance by targeted therapies such as endothelin receptor antagonists should further improve treatment options for the management of PAH. Current treatment algorithms for PAH recommend bosentan as first-line treatment for PAH in functional class III. Recent many trials suggested that endothelin receptor antagonist, bosentan, caused good results in idiopathic PAH and PAH associated with chronic thromboembolism, collagen diseases, and congenital heart diseases.