A profusion of circulating candidate biomarkers in heart failure is currently being investigated. Although all will advance our insight into the pathophysiology of heart failure, their potential clinical utility will depend on satisfaction of three key criteria. Assays must be accessible, reliable, and affordable. Secondly, the marker must provide information about cardiac function and prognosis not otherwise available. Finally, measurement of the marker must demonstrably lead to improved management and better clinical outcomes. Despite many promising candidates requiring fuller investigation, currently, only the natriuretic peptides satisfy these requirements.