Heart failure is a complex clinical syndrome that manifests itself with signs and symptoms which are neither sensitive nor specific for the diagnosis of heart failure. Natriuretic peptides and in particular b-type natriuretic peptide (and nt-proBNP) are widely used in clinical practice around the world as a maker of heart failure. BNP is primarily released from the left ventricle in response to pressure and volume overload. The strongest evidence for the use of BNP is to rule in or rule out heart failure as cause of breathlessness in people who present to the emergency room. There is enthusiasm for use of BNP as a marker of heart failure severity as well as a predictor of outcomes in people with heart failure and trials are ongoing. Nesiritide, a recombinant form of BNP is currently being tested as a possible treatment in people with acutely decompensated heart failure.