OBJECTIVES: To determine the cost-effectiveness of endovascular aneurysm repair (EVAR) versus open surgical repair (OSR) for acute (ruptured or symptomatic intact), infrarenal abdominal aortic aneurysm (AAA) in an emergency setting. METHODS: A two-stage cost-utility model was developed for the recent appraisal of EVAR by the National Institute for Health and Clinical Excellence in England and Wales to capture the lifetime costs and benefits of EVAR for non-ruptured AAA. This model was adapted to capture the costs and health outcomes of EVAR for acute AAA. The model population represented a 70-year-old, fit for open surgery, with an acute AAA. 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, complications and secondary interventions. Primary data sources included a meta-analysis of 23 studies and the EVAR I randomised controlled trial. 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: EVAR dominates OSR in the base case analysis. The average QALY gain at 30 years post surgery was 0.064 for EVAR compared with OSR. The results were not sensitive to changes in parameters. CONCLUSIONS: The results suggest that EVAR for acute AAA is cost-effective versus OSR with probabilities approaching 100% based on willingness-to-pay thresholds of £20,000 and £30,000.