The dual endothelin receptor antagonist, bosentan, is an orally active therapy, which has been proved to be effective in the treatment of pulmonary arterial hypertension (PAH). This review critically addresses and highlights pharmacological aspects of bosentan such as safety, tolerability and drug interactions. The biological basis of its mode of action is demonstrated in preclinical studies on animal models of PH and an up-to-date review of clinical data is provided, supporting its practical use with a view to achieve optimal treatment goals. Major pivotal randomized placebo-control clinical trials are discussed, together with recently published data concerning its promising role as part of combination therapy. Furthermore, recent patents of novel pharmaceutical interventions in the field of PAH, expanding treatment options, are presented.