Anti-thrombotic therapy improves the prognosis of patients with unstable angina. Two clinical trials have evaluated the clinical efficacy of tirofiban or tirofiban plus heparin in the treatment of unstable. However, high price for tirofiban prompts the question of whether the additional effectiveness is worth the additional drug cost. OBJECTIVE: This medical decision analytic model is to investigate the cost-effectiveness of tirofiban plus heparin in treating unstable angina relative to heparin only. METHOD: Parameters of treatment efficacy used in the cost-effectiveness model were primarily from the report of PRISM-PLUS (the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Syndrome) trial. Other parameters (cost, life expectancy, and quality of life) were cited from the published literature. The time frame for this model is 1-month initial episode of unstable angina and 1-year follow-up. It was assumed that there was no additional cost difference between two groups after one-year follow-up. Effectiveness was measured as quality adjusted life years (QALYs). RESULTS: A patient in tirofiban plus heparin group had both higher total costs ($25,467 versus $24,805) and a lower mortality rate (5.89% versus 6.83%) than a patient in heparin only group. The incremental cost-effectiveness ratio was $10,417/QALY at 3% discount rate. In the sensitivity analysis, the incremental cost-effectiveness ratio was only sensitive to the tirofiban acquisition cost. CONCLUSION: Treating unstable angina with tirofiban plus heparin is cost-effective compared with the traditional heparin-only therapy.