To identify the factors that determine operative mortality and long-term survival, we analyzed the data from 3,311 patients who underwent surgical therapy for unstable angina according to clinical presentation. Overall operative mortality was 3.9% and no differences in operative mortality were found between patients with coronary insufficiency, new-onset angina, rest angina, or changing patterns of angina. Logistic regression analysis indicated that age, left ventricular score, and presence of a left main stenosis in a left dominant circulation were related to operative mortality. The 7 year cumulative survival rate was 79%. Features predictive of long-term outcome by Cox analysis included left ventricular score, congestive heart failure score, other illness, extent of coronary disease, and cardiomegaly. Operative mortality of those patients who underwent coronary bypass during their initial hospitalization with unstable angina was similar to that of patients who were discharged and readmitted for operation at a later date. Thus, patients with unstable angina demonstrate a relatively low operative mortality, which is unrelated to the clinical presentation. Long-term survival is primarily determined by clinical and angiographic markers of left ventricular dysfunction, associated illness, and the extent of coronary disease.