Ten years ago brain natriuretic peptide (BNP), the second compound of a family of polypeptide hormones named natriuretic peptides was identified, This peptide has great pathophysiologic importance as a stress-induced cardiac hormone secreted from ventricles, and it rises in several cardiac diseases, It promotes natriuresis and diuresis, acts as a vasodilator, and antagonizes the vasoconstrictor effects of the renin-angiotensin-aldosterone system. The measurement of this peptide in blood by immunoassay has shown promise over the past decade in clinical diagnosis and prognosis. Because heart failure is a major health problem worldwide, BNP is proposed as a biochemical marker that might provide a useful screening test to select patients for further cardiac investigations, Such a hormone assay is inexpensive and available, The implications of BNP in diagnosis, prognosis, and therapy will be reviewed.