OBJECTIVES: The TRITON-TIMI 38 Trial demonstrated that in patients with acute coronary syndromes (ACS) undergoing planned percutaneous coronary intervention (PCI), prasugrel compared to clopidogrel significantly reduced the rate of ischemic events over up to 15 months of follow-up, though there was an increased risk of major bleeding.   Three risk factors for bleeding identified in the trial were a prior history of stroke/TIA, age ≥75 years, and body weight <60 kg.  Patient-level data from TRITON was used to compare hospitalization costs in South Korea for patients without these risk factors for bleeding, who were randomized to prasugrel vs. clopidogrel.  METHODS: Details regarding hospitalizations for all patients from 8 high enrolling countries (US, Australia, Canada, Germany, Italy, Spain, UK, France; n=3373 prasugrel, 3332 clopidogrel) were collected prospectively. The US diagnosis-related group codes were assigned to all hospitalizations, to which 2009 South Korean unit costs were applied.  Estimates of incremental costs associated with PCI-associated periprocedural MIs and PCI- and CABG-associated bleeding events were added separately, based on published U.S. data. RESULTS: Prasugrel was associated with a 17,723 KRW per patient increase in costs due to bleeding, and an 8,377 KRW decrease in costs due to reduced periprocedural MI, during the index hospitalization.  Per-patient costs from hospitalization for MI (not involving revascularization) during the follow-up period were 291,022 KRW lower with prasugrel compared to clopidogrel, and costs associated with revascularization hospitalizations during follow-up were 505,032 KRW lower.  Costs from follow-up bleeding events were 52,082 KRW higher for prasugrel, while aggregate hospitalization costs were 293,656 KRW lower. CONCLUSIONS: For ACS patients with planned PCI,  the lower ischemic event rate with prasugrel yields a reduction in overall hospitalization costs, despite increased costs from bleeding.  These results have implications for the cost-effectiveness of alternative antiplatelet strategies for ACS patients undergoing PCI in South Korea.