OBJECTIVES: Antiplatelet agents play an important role in preventing recurrent stroke. Aspirin is the most widely studied and used for this purpose. Clinical trials indicated that ticlopidine, clopidogrel, and a combination regimen, aspirin plus modified-release dipyridamole (ASA+MR-DP), are also effective for prevention of recurrent stroke. However, these new antiplatelet agents are more expensive than aspirin. Our study aimed to evaluate their cost-effectiveness ratios relative to aspirin in Taiwan. METHODS: Markov model is developed to measure the clinical benefit and economic consequences of the following strategies to treat patients aged 65 years or older who were at high-risk of recurrent stroke: 1) aspirin 100mg once a day; 2) aspirin 25mg plus modified-release dipyridamole 200mg (ASA+MR-DP) twice a day; and 3) clopidogrel 75mg once a day. Input data were obtained from literature review. The analysis was done in BNHI’s perspective. Cost and quality-adjusted life-year (QALY) are primary outcomes measured. The time frame is two years. RESULTS: The use of aspirin/dipyridamole combination was effective and slightly more costly compared to the use of aspirin: direct cost per one patient is NTD45,310, and estimated QALY for one patient is 1.948 years; in aspirin group: direct cost per one patient is NTD 33,623, and estimated QALY for one patient is 1.946 years. The Incremental cost-effectiveness ratio (ICER) between aspirin and ASA+MR-DP is NTD1,889,544 per QALY. While the incremental cost-effectiveness ratio between aspirin and clopidogrel is NTD9,699,399 per QALY. According to the sensitivity analyses, the efficacy and drug prices of antiplatelet agents are key factors to determine the ICER compared with aspirin. CONCLUSIONS: Comparing new antiplatelet agents to aspirin, our results show that using new drugs is cost-effective, i.e. using new drug has better outcome, but introduces higher direct cost.