The heart is a major site of natriuretic peptides (NP). Atrial and brain natriuretic peptide (ANP and BNP) are predominantly produced by atria and ventricles. C-Natriuretic peptide (CNP) is also found in heart tissue. ANP and BNP are produced by cardiomyocytes and fibroblasts. Cardiac fibroblasts also secrete CNP. Three NP-receptors (NPR-A, NPRB, NPR-C) are expressed in heart atria and ventricles. Baseline plasma BNP is a sensitive predictor of morbidity and mortality in heart failure and changes in BNP over time are associated with corresponding changes in subsequent mortality and morbidity. Plasma BNP, and to a lesser extent ANP, is also a strong cardiovascular risk marker in patients with essential hypertension and left ventricular hypertrophy without left ventricle dysfunction or overt renal disease. However, evidence to date suggests that plasma BNP levels should not be viewed as a diagnostic test for chronic heart failure and sequential assays of BNP have not been shown to be useful in the follow-up or the initiation of appropriate therapy. However, patients who present with dyspnea with unclear but suspected cardiac etiologies may be considered to have venous blood taken for the measurement of BNP level to assist with diagnostic decision and therefore appropriate management of the dyspnea. BNP level is however not a stand-alone test and must be used in conjunction with careful clinical evaluation and in patients with an intermediate pre-test likelihood of heart failure.