Acutely dyspneic patients are challenging, because their symptoms can be due to cardiac, pulmonary or other diseases. B-type natriuretic peptide testing offers higher diagnostic accuracy (85%-90%) than clinical assessments for identifying heart failure as the cause of dyspnea. On the other hand, the high clinical sensitivity and negative predictive value of natriuretic peptides permit to rule out heart failure with an accuracy > 90%. Natriuretic peptides are the most powerful, single prognostic markers of complications associated with acute dyspnea and permit the early recognition of high-risk patients. It has been shown that systematic natriuretic peptide testing reduces the economic expenses associated with clinical management of acutely dyspneic patients. Finally, whether these biomarkers could be used to guide heart failure therapy in the acute setting remains to be elucidated.