Unstable angina is a broad clinical diagnosis that includes patients at different levels of risk for an unfavorable outcome. Although, as in other categories of coronary artery disease, the state of left ventricular function and the extent of coronary artery disease will determine long-term prognosis, recognition of clinical markers of an early unfavorable course may be of value in defining management strategies. This review focuses on the relevance of baseline clinical characteristics and noninvasive data in assessing the prognostic significance of unstable angina in light of its presenting features. Recurrence of chest pain within 48 h after admission carries a reduction in likelihood of survival of about 20% in patients with progressive or prolonged angina. Similarly, ECG changes on admission have a negative prognostic implication, particularly in rest angina, as they predict recurrence of ischemia, myocardial infarction or need for revascularization in 80% of the patients. In variant angina, determinants of prognosis are level of disease activity, as judged by recurrence of pain, ECG changes and use of calcium channel antagonists. Patients with angina after a myocardial infarction who have more than one episode of either angina or silent ischemia in 24 h have a 10% reduction in probability of survival during the 1st year compared with that of asymptomatic patients. An abrupt course, or the rapidity with which symptoms develop, is the main determinant of prognosis in new onset angina. Thus, recurrent angina and ECG changes appear to be relevant prognostic markers in the patient subsets considered; if these are present, early coronary angiography must be performed and revascularization procedures should be considered without delay.