Fewer than one third of patients presenting to the emergency department with complaints of chest pain have an acute coronary syndrome. The electrocardiogram provides a specific diagnosis only in 40% of patients with acute myocardial infarction. The presence of regional wall-motion abnormalities at echocardiography in patients without known coronary artery disease is a moderate indicator of an increased likelihood of acute myocardial ischemia or myocardial infarction with a positive predictive accuracy of about 50%. More important, the absence of regional wall-motion abnormalities identifies a subset of patients unlikely to have a myocardial infarction with a negative predictive accuracy of about 95%. Echocardiography can provide incremental prognostic information to identify patients at risk of early or late cardiac events, even after consideration of clinical, historical, and electrocardiographic variables. The application of new contrast agents to echocardiography will probably allow an early and more accurate evaluation of patients with chest pain of uncertain significance.