Background Patients with unstable angina (UA) and non-ST-elevation myocardial infarction (NSTEMI) remain at risk for death and cardiac ischemic events after being discharged from the hospital. Methods We examined whether the Thrombolysis In Myocardial Infarction (TIMI) risk score for UA/NSTEMI, ascertained at presentation in patients enrolled in the TIMI 11B and Efficacy and Safety of Subcutaneous Enoxaparin in Unstable Angina and Non-Q-Wave MI (ESSENCE) trials, could be used to identify patients at high risk for major cardiac events after hospital discharge. Results There were a total of 1218 major cardiac events, defined as death, nonfatal myocardial infarction, or urgent revascularization, by day 43. Of these events, 336 (28%) occurred in patients after they were discharged from the hospital. Use of the TIMI risk score for UA/NSTEMI revealed a progressive, statistically significant increase in the rate of events after leaving the hospital as the patients' baseline level of risk increased (P <.001 for χ² test for trend). For patients with a risk score of 5 to 7, treatment with enoxaparin during the acute phase was associated with an odds ratio of 0.51 (95% CI 0.29-0.91) for the occurrence of death and cardiac ischemic events after hospital discharge. Conclusions More than one fourth of the major cardiac events that will occur in the first 6 weeks occur after discharge from the hospital. Stratification at presentation on the basis of the TIMI risk score for UA/NSTEMI can be used to identify patients at high risk for these events. Among patients at high-risk, acute-phase treatment with enoxaparin significantly reduces the risk of major cardiac events after leaving the hospital. (Am Heart J 2002;143:966-70.)