Cardiac biomarkers are commonly used in clinical practice. The two most common biomarkers used in clinical cardiology are cardiac troponin for detecting myocardial ischemia/injury and B-type naturetic peptide (BNP) for detecting heart failure. Cardiac troponin is released into the blood stream with myocardial injury and newer assays with greater sensitivity (e.g., high-sensitivity cardiac troponin [hs-cTn]) may lead to increased detection of myocardial injury, but they may also result in over diagnosis of myocardial infarction. Creatine kinase MB fraction (CKMB) has been the traditional cardiac biomarker of injury used in clinical trials, but it is being replaced by some measurement of troponin. BNP and its precursor, NT-proBNP, are valuable in the diagnosis and prognosis of heart failure and are currently being evaluated as markers of therapeutic response. With the introduction of valsartan/sacubitril, an angiotensin receptor and neprilysin inhibitor (ARNI), NT-proBNP has become a better biomarker because neprilysin inhibition will raise BNP but not NT-proBNP. Although changing biomarkers as end points in cardiovascular outcomes trials has been proposed to decrease the size of these trials, whether biomarker response is truly predicative of outcomes remains to be determined. Clinical outcomes are still needed to define the risk and benefit of new therapies.