Macitentan (Opsumit®) is an orally active, potent, dual endothelin (ET) receptor antagonist that is indicated for the treatment of pulmonary arterial hypertension (PAH). In the pivotal SERAPHIN trial in patients aged ≥12 years with PAH, the risk of first PAH-related event or all-cause death (primary composite endpoint) was significantly reduced by 45 % with oral macitentan 10 mg once daily versus placebo. Macitentan significantly reduced the risk of the primary composite endpoint across various patient subgroups. The risk of all-cause hospitalization and PAH-related hospitalization was also significantly reduced by macitentan, according to post hoc analysis. Macitentan was generally well tolerated in SERAPHIN. In conclusion, macitentan is an important option for the treatment of PAH.