Acute coronary syndromes (ACSs) represent the acute life-threatening phases of coronary heart disease. Clinical symptoms, EKG, and CK-MB measurements are frequently insufficient to evaluate patients without persisting ST elevations. Serial determinations of troponin T or troponin I after arrival in hospital disclose minor myocardial injury in patients presenting as unstable angina. This finding allows the currently best risk stratification and may contribute to cost-effectiveness. Without elevated troponins the risk for death or myocardial infarction during 30 days follow-up is not more than 1%. The lack of elevated troponins does not implicate that these patients do not have coronary artery disease. Patients with positive evidence of troponins represent a high-risk group who should be hospitalized and further evaluated, because the risk for myocardial infarction and death in 30 days is approximately 20%. Current studies indicate that early revascularization under glycoprotein IIb/IIIa antagonists represent the optimal treatment.