Cardiovascular disease today remains a formidable foe affecting 1 in 3 Americans. The emergence of cardiac biochemical markers has provided clinicians unique insight into the state of the myocardium. In fact, cardiac biomarkers now represent an essential criterion in the definition of acute myocardial infarction. There has been impressive development of efficient and reliable assays to detect biomarkers in the serum. Together with patient history and electrocardiographic analysis, the invaluable information gained from serum cardiac biomarkers supports diagnosis, therapy selection, and determination of prognosis. Biomarkers such as troponin and creatine kinase MB have received well-deserved attention for their ability to detect myocardial ischemia. Clinicians today use cardiac markers to identify ischemia as well as alternate clinical states. B-type natriuretic peptide, for instance, reflects myocardial stretch as seen in heart failure exacerbations and may well have promising prognostic significance. The purpose of this review is to discuss current and emerging cardiac biomarkers in acutely ill patients. The advantages and disadvantages of biomarkers will also be presented in the context of their clinical uses. Present markers are highly sensitive and specific to myocardial injury; however they do not specifically identify the method of injury. An exciting potential exists for future biomarkers to demonstrate enhanced specificity and earlier detection of compromised myocardium.