Background: Patients with minor ischemic stroke or transient ischemic attacks (TIAs) are often treated with dual antiplatelet therapy regimens as part of secondary stroke prevention. Clopidogrel, an antiplatelet used in these regimens, is metabolised into its active form by the CYP2C19 enzyme. Patients with loss of function (LOF) mutations in CYP2C19 are at risk for poorer secondary outcomes when prescribed clopidogrel Aims: We aimed to determine the cost effectiveness of three different treatment antiplatelet regimens in ischemic stroke populations with minor strokes or TIAs and how these treatment regimens are influenced by the LOF prevalence in the population. Methods: Markov models were developed to look at the cost effectiveness of empiric treatment with aspirin and clopidogrel versus empiric treatment with aspirin and ticagrelor, versus genotype guided therapy for either 21 or 30 days. Effect ratios were obtained from the literature and incidence rates and costs were obtained from the national data published by the Singapore Ministry of Health. The primary endpoints were the incremental cost-effectiveness ratios (ICERs). Results: Empiric treatment with aspirin and ticagrelor was the most cost-effective treatment. Genotype guided therapy was more cost effective than empiric aspirin and clopidogrel if the LOF was above 48%. Empiric ticagrelor and aspirin was cost saving when compared to genotype guided therapy. Results in models of dual antiplatelet therapy for 30 days were similar. Conclusion: This study suggests that in patients with minor stroke and TIA planned for dual antiplatelet regimens, empiric ticagrelor and aspirin is the most cost-effective treatment regimen. If ticagrelor is not available, genotype guided therapy is the most cost-effective treatment regimen if the LOF prevalence in the population is more than 48%.