Cardiac troponins not only allow for risk stratification and guidance of therapy in unstable angina and non-Q-wave acute myocardial infarction but also may be useful in the diagnostic workup and monitoring of patients with ST-segment elevation myocardial infarction. In clinical practice, troponins are used for confirmation and monitoring of myocardial infarction, noninvasive prediction of reperfusion success after thrombolytic therapy, and noninvasive estimation of infarct size. Accumulating evidence suggests that the measurement of cardiac troponins on admission may represent a relatively novel application that is useful for early risk stratification and prediction of reperfusion success after thrombolysis or primary percutaneous coronary interventions. Potential mechanisms of the predictive power of cardiac troponins are discussed.