OBJECTIVES: Results from the pivotal Clopidogrel for the Reduction of Events During Observation (CREDO) trial demonstrated that one year of clopidogrel following a percutaneous coronary intervention (PCI) significantly reduced the absolute combined risk of death, MI, or stroke by 3%. Utilizing Canadian Case Mix Group (CMG) costing, we sought to determine the incremental cost-effectiveness per event prevented over one-year and estimate the incremental cost-effectiveness per life year gained (LYG) for a clopidogrel + ASA strategy vs. ASA alone before and after PCI. METHODS: Canadian health care resource utilization costs were obtained from Case Mix Group costing from the 2003 Health Funding and Costing Branch of Alberta Health and Wellness Report. Cost-effectiveness was expressed as the incremental cost per event prevented (ICERep) or cost per life year gained (ICERlyg). Bootstrap methods were used to estimate the joint distribution of cost and effectiveness differences between the two arms and obtain 95% confidence intervals (CI). The Canadian costs of clopidogrel and aspirin were C$2.40 per 75 mg, and C$0.05 per tablet respectively. Life expectancy in trial survivors was estimated from discounted Framingham and Saskatchewan data. RESULTS: Total one-year average cost per patient in clopidrogrel + ASA and ASA alone arms were C$21,241 and C$20,786 respectively; a difference of C$455 (95% CI = -C$495 to C$1,391). The ICERep was C$15,040 with 59% of bootstrapped ICERs less than C$20,000 (87% less than C$50,000). The ICERlyg using Framingham estimates was C$2,980 with over 96% of bootstrapped ICERs less than C$20,000 (98% less than C$50,000). The ICERlyg using Saskatchewan estimates was C$2,369 with over 97% of bootstrapped ICERs less than C$20,000 (nearly 99% less than C$50,000). CONCLUSION: Treatment with clopidogrel for 12-months following PCI is highly cost-effective in the Canadian health care system.