Unstable angina is one of the most common reasons for hospital admission in the United States and causes substantial morbidity and mortality. Diagnosis of unstable angina is complicated by the dynamic range of presentations, which can vary between atypical chest pain and acute myocardial infarction. Overcautious management can result in unnecessary hospital admission, whereas inappropriate conservative strategies can cause cardiac injury and death. To define treatment strategies for these patients, the US Agency for Health Care Policy and Research in March 1994 published guidelines on the diagnosis and management of unstable angina. The emphasis is on diagnosis or exclusion of coronary artery disease, establishment of the patient's risk for adverse outcome, and triage to the most appropriate treatment regimen. The guidelines emphasize the use of aspirin, heparin sodium, nitroglycerin, and beta-blockers as the core therapy. Appropriate strategies are reviewed, starting with intensive medical management and ending with patient care after discharge. Many physicians will probably modify their approach to the diagnosis and treatment of unstable angina on the basis of these new guidelines.