In low- and intermediate-risk patients with unstable angina pectoris (UAP) and non-ST-elevation acute myocardial infarction (NSTEAMI), routine early invasive management with coronary angiography does not decrease the risk of death or AMI. The economic consequences of this strategy in low- and intermediate-risk patients are unknown. We applied a risk prediction rule to a multihospital practice database and to the population of the Thrombolysis In Myocardial Ischemia trial, phase IIIB (TIMI 3B), which compared early invasive with conservative therapy for UAP and NSTEAMI. We then analyzed the effect of an early invasive strategy with regard to the composite end point of death, AMI, or rehospitalization for ischemia at rest. A logistic regression model was used to compare outcomes in patients with high versus low or intermediate risk scores. The costs and benefits of early invasive management in low- or intermediate-risk patients were assessed. In the practice database, 56% of patients with UAP and NSTEAMI who had low or intermediate risk scores underwent early cardiac catheterization, although early invasive management of these lower risk patients has not been associated with a reduction in the rate of death or MI. In TIMI 3B, when rehospitalization for ischemia at rest was added to the composite end point, invasive management was superior to conservative management at 42 days (p = 0.005) and at 1 year (p = 0.03). If all low- or intermediate-risk patients randomized to conservative therapy in that trial had been treated instead with an early invasive strategy, an estimated 5.4% of rehospitalizations would have been avoided. Within TIMI 3B, such a routine invasive strategy would have resulted in an additional cost of 2,695,700 US dollars with no effect on death or AMI, but it would have led to 34 fewer rehospitalizations. This expenditure of 79,285 US dollars per hospitalization prevented far exceeds the monetary cost of rehospitalization (14,000 US dollars). Although common in clinical practice, routine early invasive management of low- or intermediate-risk patients with UAP generates substantial health-care costs without a mortality benefit or decrease in the risk of AMI. Unless the incremental benefit in quality of life from prevented rehospitalizations for UAP is judged to be worth the large incremental cost (79,285 US dollars per hospitalization prevented), such a strategy is unlikely to be cost effective.