Interleukin-6 (IL-6) is associated with abdominal aortic aneurysm (AAA) development and is an independent risk factor for cardiovascular mortality. We tested the hypothesis that aneurysm repair reduces circulating IL-6 by comparing concentrations in patients with large AAA awaiting repair (n = 50) with patients having undergone open (n = 34) or endovascular (n = 66) repair. Only open repair was associated with a significant reduction in IL-6 (p = 0.025). These results suggest that AAAs remain biologically active following endovascular repair. Aneurysm-derived IL-6 may have serious implications for cardiovascular health, and attention should be directed to modifying cardiovascular risk factors in these patients, even after successful aneurysm repair. (c) 2008 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.