OBJECTIVES: To determine the cost-effectiveness of endovascular aneurysm repair (EVAR) versus open surgical repair (OSR) for non-ruptured, infrarenal abdominal aortic aneurysm (AAA) in an elective setting. The analysis was conducted for the recent appraisal of EVAR by the National Institute for Health and Clinical Excellence in England and Wales. METHODS: A two-stage cost-utility model was developed from an NHS perspective to capture the lifetime costs and health outcomes of EVAR. The model population represented a 70-year old, fit for open surgery, with an AAA at least 5.5 cm in diameter. A decision-tree model captured the short-term costs and health outcomes of patients during the first 30-days post-repair, followed by a Markov model, with monthly cycles during the first 24 months and yearly cycles thereafter, until death. Clinical endpoints included mortality and complications. Primary data were derived from the EVAR I randomised controlled trial where reported. To reflect current clinical practice other sources including retrospective patient data were used. Costs were applied from trial data and national reference sources. A discount rate of 3.5% was applied to costs and health outcomes. Univariate and multivariate sensitivity analyses were performed for all parameters. An incremental cost-effectiveness ratio (ICER) reflecting incremental lifetime costs per quality adjusted life year (QALY) gained was calculated for the base-case analysis. RESULTS: Base case analysis, resulted in an ICER of £15,681 per QALY for EVAR versus OSR. The average QALY gain at 30 years post surgery was 0.072 for EVAR compared with OSR. Results were most sensitive to the relative risk of short-term mortality, cost of the EVAR device and long-term rate of secondary interventions in the EVAR group. CONCLUSIONS: The results suggest that EVAR is cost-effective for non-ruptured AAA versus OSR with a probability of 66% and 60% based on willingness-to-pay thresholds of £30,000 and £20,000, respectively.