OBJECTIVES: This study calculated 1-year total health care costs for ACS patients and evaluated differences based on treatment strategy for patients during their initial hospitalization.  METHODS: Commercially insured individuals, aged 18-64, participating in a large claims database were identified by a hospitalization with an ACS diagnosis between January 2004 and December 2005 with a 1-year follow-up period.  Patients who had an ACS diagnosis in the prior 12-month to their initial ACS hospitalization were excluded.  Patients were divided into 3 groups by treatment strategy during the initial hospitalization: MM, PCI or CABG.  Multivariate linear regression was performed to assess the adjusted cost differences across these 3 groups.  RESULTS: A total of 19,617 ACS patients were identified, of which 52% (n=10,152) were managed by medical therapy, 40% (n=7962) by PCI and 8% (n=1539) by CABG.  Mean length of stay and per-patient expenditures during the initial hospitalization for the MM, PCI and CABG groups were 1.9 days/$10,878, 3.3 days/$31,900 and 9.3 days/$68,333, respectively.  One-year follow-up costs were $25,131 for MM, $21,039 for PCI, and $22,677 for CABG, where 46%, 42% and 46% of these costs were due to rehospitalization, and 4.7%, 10% and 5.9% were due to ACS-related prescription drug costs.  Controlling for differences in demographics and clinical characteristics, CABG patients had approximately $52,365 greater 1-year total health care costs compared to MM patients (p<0.01) while PCI patients had approximately $15,952 higher total health care costs than MM patients (p<0.01). Factors associated with increased costs included gender, age, comorbidities, initial hospitalization diagnosis, treatment strategy and prior health care costs.  CONCLUSIONS: Total 1-year health care costs are substantial for working-aged patients newly diagnosed with ACS and significantly different across the three treatment groups.  Significantly higher costs were observed in patients managed interventionally, particularly by CABG, with the majority of these costs incurred during the initial hospitalization.