The role of the natriuretic peptide assay: brain natriuretic peptide (BNP) and N-terminal pro-BNP natriuretic peptide (NT-proBNP) in the diagnosis and prognosis in patients with heart failure has been approved by the Food and Drug Administration (FDA). This dosage is more and more frequently requested in the hospital environment, particularly in the context of the differential diagnosis of dyspnea in a patient presenting to the emergency department. The difficulty for the biologist is to choose between the dosage of BNP biologically active hormone and the assay of NT-proBNP, non-active peptide. This is a bibliographic study that consists of the analysis of different clinical and bibliographic studies that have compared the dosage of these two cardiac markers. The BNP assay is faster and is characterized by a lower glomerular filtration dependence compared to NT-proBNP and a shorter half-life that allows to rapidly monitor its variations. However, because of its excellent stability, the NT-proBNP makes it possible to avoid the false negatives due to the delay of delivery in the university centers. It is performed by automated technique which allows an easy realization of a large number of tests and it also allows a better detection of the early stages of heart failure.