Objective: To assess the cost-utility and budget impact of transcatheter aortic valve implantation (TAVI) compared with surgical aortic valve replacement (SAVR) in patients with severe aortic stenosis Methods: A hybrid model between decision tree and Markov model was used to compare TAVI and SAVR in 2 groups of patients with severe aortic stenosis, intermediate and high surgical risks. The societal perspective was taken into consideration; therefore, direct medical costs and direct non-medical costs were included. Direct medical costs comprised of costs of surgery, operation and complications (both outpatient and inpatient costs). Direct non-medical costs comprised of costs of transportation, accommodation, food, and caregiver. Those costs were collected either from electronic hospital databases or from patients’ interview of 5 hospitals (Siriraj, Chulalongkorn, Maharaj Nakorn Chiang Mai, Prince of Songkla, and Ramathibodi hospitals). Utility data were also directly collected from patients who visited above 5 hospitals. Probability data were obtained from literature review. Outcomes were measured in terms of life year and quality-adjusted life-year (QALY). All costs and outcomes were discounted with an annual discount rate of 3%. Incremental cost-effectiveness ratio (ICER) was estimated. A variety of sensitivity analyses such as deterministic sensitivity analyses (one-way sensitivity analysis, threshold analysis, scenario analysis), and probabilistic sensitivity analysis were performed. Budget impact analysis was also conducted based on the data from literature review and epidemiological data in Thailand. A scenario of no TAVI used (85%) versus TAVI used (15%) for treating severe aortic stenosis treatment was analyzed in base-case analysis. Sensitivity analyses were also performed by 5% increase in TAVI uptake each year, and the reduction in TAVI cost. Results: The base-case results showed that life-time total cost of TAVI and SAVR were 1,717,132 THB and 893,524 THB, respectively, while the QALYs were 4.88 years for TAVI and 3.98 years for SAVR. This yielded the estimated ICER of 906,937 THB per QALY for patients with intermediate risk. In case of patients with high risk, life-time total cost was 1,551,895 THB for TAVI and 548,438 THB for SAVR, while the QALYs were 3.15 years for TAVI and 2.31 years for SAVR. This yielded the estimated ICER of 1,196,191 THB per QALY. Comparing with the ceiling ratio of 160,000 THB per QALY, TAVI was not a cost-effective treatment for both groups with intermediate and high risks. The chance of TAVI being cost-effective would increase with higher level of the willingness to pay. In addition, TAVI valve was the most influential factor on the estimated ICER. The ICER was declined to 160,000 THB per QALY when the reduction in cost of TAVI valve was about 63.5% with the remaining cost of 390,583 THB and 81.3% with the remaining cost of 199,655 THB for patients with intermediate and high risks, respectively. The base-case results of budget impact analysis showed that the net budget impact (NBI) on average was 136,561,166 THB per year. The NBI would increase to 171,119,480 THB per year and 196,391,442 THB per year with an increase in TAVI uptake of 5% per year and 10% per year, respectively. The extension of TAVI treatment to the population aged 70 years and older increased the NBI to 403,008,823 THB per year for constant TAVI use of 15%. An increase in the TAVI uptake rate of 5% and 10% per year results in the NBI of 504,994,664 THB per year and 579,575,337 THB per year, respectively. The NBI would decline depending on the cost of TAVI valv. With the cost of TAVI valve of 470,069 THB (reduction by 60%), the NBI was decreased to 38,727,267 THB per year, 47,890,464 THB per year, and 54,366,994 THB per year when the TAVI use was 15% constant, or 5% yearly increase, or 10% yearly increase, respectively. Conclusion: The findings of the study indicated that TAVI is not a cost-effective technology at the ceiling ratio of 160,000 THB per QALY. The high cost of TAVI valve is of great important factor. Therefore, it needs several strategic mechanisms such as price negotiation, appropriate patient selection because TAVI is a life saving for severe aortic stenosis patients who are inoperable or have high risk for operation.