OBJECTIVE: There is a limited amount of literature examining the burden and cost of illness of acute coronary syndrome (ACS) in the managed care population. The goal of this study was to estimate the total cost of health care utilization (health plan plus patient) in the 12-month period following newly onset ACS. The demographic and health characteristics of these patients are compared with the similar data from 2 large clinical trials: CURE (Clopidogrel in Unstable Angina to Prevent Recurrent Events) and PROVE IT-TIMI 22 (Pravastatin or Atorvastatin Evaluation and Infection Therapy Thrombolysis in Myocardial Infarction 22). METHODS: A retrospective claims analysis was conducted for the 2-year period from July 1, 1999, through June 30, 2001. ACS was defined as an emergency room visit or hospitalization with a primary International Classification of Diseases, 9th Edition/Revision (ICD-9) diagnosis of 410.xx (acute myocardial infarction) or 411.1x (intermediate coronary syndrome). Patients were required to be free of any ACS claim in the previous 6 months. Patients without 6 months of prior continuous enrollment or those patients younger than 18 years were excluded. Patients were followed up to 12 months to identify total medical and pharmacy costs, revascularization procedures, and medication use. RESULTS: A total of 13,731 patients met the inclusion criteria, yielding 133,814 months of follow-up (mean: 9.75 months per patient) and representing approximately 0.4% of the managed care members in the database during the study period. The mean age was 54 years and 68% were male. The total direct cost incurred by the health plan and patients was $309 million ($2,312 per patient month of follow-up); 72% of total costs were attributable to hospitalizations. The majority of costs were medical ($286 million, 93%), and $23 million (7%) were pharmacy costs. Fifty-one percent of patients had a revascularization procedure, which was typically performed during the index hospitalization (median time to revascularization was 0 days). Coronary artery stent implantation was the most common revascularization procedure (68%). During follow-up, 490 patients (3.6%) had a detectable death, 58% of patients received a beta-blocker, 60% received one or more cholesterol-lowering medications, and 36% of patients received clopidogrel therapy. Aspirin therapy was not measured. CONCLUSIONS: These managed-care patients with newly onset ACS incurred substantial costs in the 12 months following initial presentation. Revascularization was a common therapeutic intervention for these patients. There appear to be opportunities to improve medication therapy after an acute ACS event. There were some demographic and health characteristics that were different in these commercially insured patients from those in 2 large clinical trials.