Brain or B-type natriuretic peptide (BNP) is one of the new biomarkers employed within the last decade to help clarify difficult cardiovascular problems. Plasma BNP is elevated in cardiac ventricular dysfunction and plays a key role in protecting the body from volume overload by maintaining renal function and sodium balance. Studies in patients with pulmonary arterial hypertension (PAH) have demonstrated that plasma BNP levels are raised proportionally to the extent of right ventricular (RV) dysfunction. There is growing evidence that BNP may be a potential biomarker for PAH in screening for occult disease, diagnostic evaluation, prognosis, and estimating a response to therapy. Additionally, augmentation of the natriuretic peptide system through exogenous administration of BNP or by preventing its degradation may be a promising option for the management of decompensated RV failure. Because plasma BNP levels rise in a variety of cardiopulmonary conditions and are affected by several physiological factors, BNP interpretation must not occur in isolation but rather within the context of good clinical judgment.