Subacute stent thrombosis (SAT), while uncommon, continues to produce serious clinical consequences, including major myocardial infarction (MI) in 60 70% of cases, and short-term mortality rates of 20% or higher. A number of procedural and patient factors have been shown to predict the occurrence of SAT, including longer stent length, smaller minimum luminal diameter, persistent dissection, multivessel intervention, and possibly acute coronary syndrome (ACS) presentation. Despite substantial knowledge about the clinical and technical aspects of SAT, the economic impact of these events has not been previously reported. Methods. We retrospectively reviewed 26 cases of SAT that occurred at our institution from 1998-2000. Baseline clinical and procedural data, as well as clinical outcomes for the initial hospital admissions required to treat SAT, were obtained by record review. Direct health care costs for these admissions were calculated based on hospital billing data and measured resource utilization for catheterization laboratory procedures. Results. Most cases of SAT occurred in high-risk circumstances, including ACSs, multi-stent interventions, and treatment of 3.0 mm or smaller vessels. Most patients suffered significant MIs and were treated with repeat percutaneous coronary intervention. The median time to SAT was 3.5 days, with 58% of events occurring on an outpatient basis. Median total hospital costs were $11,100 per patient, with more than half of the costs generated by the catheterization laboratory and pharmacy. Conclusions. Despite its low overall frequency, the clinical and economic costs of SAT are substantial. Specific strategies at preventing its occurrence are warranted, particularly in high-risk situations.