The heart is not only a pump, but also it is an endocrine organ. Cardiac stretch and overload stimulate the secretion of natriuretic peptides, which have a variety of beneficial actions, such as vasodilation and natriuresis. Cardiac-derived natriuretic peptides, especially B-type natriuretic peptide (BNP), have emerged as useful biomarkers for the diagnosis, and potentially the treatment, of heart failure patients. The inactive amino-terminal fragment of the BNP prohormone (NT-proBNP), which is more stable than mature BNP, has also been recognized as an aid in the diagnosis of left-ventricular systolic dysfunction. Furthermore, elevated NT-proBNP concentrations have been shown to be predictive of poor prognosis in a variety of cardiovascular diseases, suggesting that it could be useful for risk stratification of patients. This review summarizes current literature that has addressed the issue of NT-proBNP as a prognostic tool in heart failure, acute coronary syndromes and other conditions.