OBJECTIVES: Treatment of abdominal aorta aneurism (AAA) has, until recently, been performed using open surgery (OS). The introduction of EVAR can improve the short- and long-term prognosis of these patients. Our objective was to determine whether EVAR is cost-effective in the treatment of AAAMETHODS: A cost-effectiveness analysis of EVAR versus OS was performed using a simulation model (Markov model) based on the literature (essentially the EVAR-1 study) plus local expert opinion and a review of AAA treatment in Spain - published by the Spanish National HTA. The study population was a hypothetical Spanish population of patients with AAA ≥5 cm and tributaries of OS. The model calculated life years gained (LYG), quality adjusted life years (QALY) and mean cost (C) per patient at 1, 2, 3 and 4 years for each option. Indicators of cost-effectiveness derived were C/LYG and C/QALY. The analysis was performed from the perspective of the Spanish National Health Service (NHS). a discount of 3.5% was applied to the future costs and outcomes. Probabilistic Sensitivity Analysis was performedRESULTS: Preliminary results showed that EVAR was associated with a higher effectiveness, with 0.09 and 0.24 LYG at 1 and 4 years vs. OS The mean cost per patient was higher in EVAR vs. OS, with an incremental cost ranging from €3281 to €3706 depending on the different scenarios, essentially because of the higher costs for purchasing the stent graft in the EVAR option. The C/LYG of EVAR was €36,645 to €15,138 and the C/QALY gained was €29,506 to €22,450 (1 and 4 years respectively).CONCLUSIONS: EVAR is an efficient alternative to conventional surgery. From one year of follow-up onwards, the cost-effectiveness figures are below the threshold of efficiency, as defined in Spain. Further prospective results on QoL Resources utilization may improve model accuracy