Background The role of early coronary angiography in the evaluation of patients with unstable angina has been controversial. This study was designed to determine the effect of early coronary angiography on long-term survival in patients with unstable angina. Methods We reviewed the Olmsted County Acute Chest Pain Database, a population-based epidemiologic registry that includes all patients residing within Olmsted County who were seen for emergency department evaluation of acute chest pain from 1985 to 1992. Patients with symptoms consistent with myocardial ischemia qualifying as unstable angina were classified as undergoing early (≤7 days of index presentation) angiography or not. Results A total of 2264 patients with symptoms consistent with unstable angina were identified with a mean duration of follow-up of 6 years; 892 underwent early angiography. Early angiography patients were younger; less likely to have heart failure; more likely to be male, hypercholesterolemic, and smokers; had prior coronary revascularization; and had a myocardial infarction at the index presentation. After baseline differences were controlled, early angiography was associated with a reduction in all-cause long-term mortality (relative risk 0.63, 95% CI 0.53-0.74). Patients at intermediate or high risk for death or myocardial infarction at presentation were most likely to benefit from early angiography. Conclusion Early angiography in the evaluation of patients with unstable angina was associated with a reduction in all-cause mortality, particularly in intermediate- and high-risk patients, in this retrospective population-based study. (Am Heart J 2001;142:768-74.)