Acute coronary occlusion is a serious manifestation of coronary artery disease leading to significant short- and long-term morbidity and mortality. Traditionally classified as Q-wave myocardial infarction, non-Q-wave myocardial infarction, and unstable angina, these events are more appropriately termed acute coronary syndromes with and without ST-segment elevation, reflecting the diagnostic criteria used by clinicians to guide initial treatment strategies. Standard therapy with aspirin and heparin has been expanded with the low molecular weight heparin enoxaparin and the intravenous glycoprotein IIb/IIIa inhibitors eptifibatide and tirofiban. Debate continues as to whether a strategy of early intervention or initial conservative management is most appropriate. Continued clinical trials will help define optimal treatment strategies in this high-risk group of patients.