Although advances have been made in the management of heart failure (HF), hospital readmission rates remain high. Finding a simple blood test to identify HF would dramatically impact the diagnosis and treatment of this syndrome. A better understanding of the pathophysiology of HF may result in improved treatment measures. Current guidelines do not target any clinical or hemodynamic criteria to achieve before discharge. Most efforts to reduce readmissions have been focused on drugs, technology, and the use of specialty HF clinics. Brain natriuretic peptide (BNP) levels have the potential of providing diagnostic, prognostic, and therapeutic information. In addition, BNP levels appear to be associated with future cardiac events such as hospital readmission. The purpose of this article is to review the precision and accuracy of BNP measurement in those with HF, and to describe how measurement of BNP can be used in clinical practice. Ultimately, BNP testing may improve the accuracy of the diagnosis of HF and guide best treatment practices.