Biological markers released into the bloodstream by the injured cardiac myocytes have contributed over the years to the diagnosis of acute myocardial infarction. Recent evidence suggests that the measurement of even minute amounts of circulating cardiac contractile proteins may be useful in the clinical assessment of patients with heart failure. Here, we briefly discuss the clinical significance of troponin measurement in chronic heart failure, in light of the availability of a new generation of highly sensitive immunoassays that are changing our understanding and interpretation of this syndrome.