Congestive heart failure (CHF) is a leading cause of adult hospitalization in the United States, and despite advancements in treatment, the disease remains a major clinical challenge. The chief symptom of CHF is dyspnea, but in the urgent-care setting, it is often difficult to distinguish between cardiac and pulmonary causes of this symptom. B-type natriuretic peptide (BNP) is mainly synthesized, stored, and released in the ventricular myocardium and is strongly induced during ventricular-wall tension or stretch. It can be measured rapidly at the point of care and can be used to differentiate cardiac from pulmonary etiologies of dyspnea. In addition to its diagnostic utility, it also has prognostic value and may help guide the treatment of patients with CHF. Thus, it is likely that future algorithms incorporating BNP levels and other clinical indicators will become available to guide critical-care physicians in making management decisions for their CHF patients.