At present it is generally accepted that unstable angina and non-Q-wave myocardial infarction have a common underlying pathophysiology, however, clinical presentation and outcome of these syndromes depend on the location, grade and duration of myocardial ischemia. The most important difference between both syndromes is the myocardial necrosis from non-Q myocardial infarction, which may carry a higher risk death and reinfarction rate and for that reason a worse prognosis than unstable angina. Some studies suggest that the effect of antithrombotic treatment can be different in both syndromes. Nevertheless the differences do not achieve significance in most of these studies.