A HORMONE REVEALING VENTRICULAR DYSFUNCTION: B-type natriuretic peptide or Brain natriuretic peptide (BNP) is a neurohormone secreted by the ventricular myocytes in response to volume expansion and pressure overload. It is a sensitive marker of ventricular dysfunction in symptomatic and asymptomatic patients, and its dosage is correlated with the severity of the dysfunction. INDICATION FOR ITS DOSAGE IN HEART FAILURE: Since the results of recent studies, many authors recommend its routine use in heart failure, in order to confirm the diagnosis in difficult cases, assess severity, prognosis and the efficacy of treatment. Such use requires that the results of these studies be known and that the threshold value be adapted according to the age, concomitant diseases and indication of the dosage. OTHER AFFECTIONS: Its diagnostic and prognostic interest in acute coronary syndromes and hypertension is presently being studied.