Systemic sclerosis (SSc) is characterized by vascular dysfunction that may lead to pulmonary artery hypertension (PAH). The N-terminal pro-B type natriuretic peptide (NT-proNBP), a marker of cardiac failure, is a diagnostic marker of early PAH in patients with SSc without heart failure. Our aim was to determine whether NT-proBNP levels may be a useful tool to evaluate the response to bosentan therapy in patients with PAH secondary to SSc. Ten patients with symptomatic, severe PAH secondary to SSc, received bosentan, 62.5 mg twice a day for 4 weeks followed by 125 mg twice a day for 7 months. Ten patients with SSc without PAH served as controls for basal level of NT-proBNP. Blood samples were obtained before the beginning of the therapy and after 3 and 7 months of treatment. SSc patients with PAH had significantly higher serum levels of NT-proBNP than those without PAH, at baseline. After 3 and 7 months of therapy, NT-proBNP concentration showed a progressive decrease, nearly approaching statistical difference at 7 months when compared to baseline levels (P=0.953 and P=0.600). Our results show that serum NT-proBNP levels may be a useful marker for the response to bosentan therapy in patients with PAH secondary to SSc.