Pulmonary arterial hypertension (PAH) is a debilitating disease associated with significant morbidity and a high mortality if left untreated. Over the past 5 years, there have been significant advances with regard to the understanding of the pathogenesis, diagnosis and classification of PAH. The availability of newer drugs has resulted in a radical change in the management of this disease with significant improvement in both the quality of life and mortality. One of the recent drugs is an orally active dual endothelin receptor antagonist, bosentan; this drug has shown to improve the exercise capacity and survival in patients with PAH. This review article discusses the pharmacology of bosentan and summarises the current available evidence for the safety and efficacy of bosentan for the treatment of PAH.