Telomeres are specialised DNA structures present at the ends of linear chromosomes, which shorten with each successive cell division and the length of which represents cellular biological age. The aim of this study was to determine the relationship between abdominal aortic aneurysm (AAA) and white cell telomere length.Peripheral blood samples were collected from 190 patients with AAA and 183 controls. Genomic DNA was extracted from white cells and telomere lengths determined using a chemiluminescence technique.The mean white cell telomere length was significantly lower in AAA patients compared to controls (median age 66 years in both groups), with a mean difference of 189 base pairs (bp) (95% confidence interval 77 bp to 301 bp, P=0.005). This relationship between case-control status and mean telomere restriction fragment (TRF) length did not change after adding other risk factors into a multiple regression model. The risk of having AAA doubled in patients with a mean TRF length in the lowest quartile compared to patients with a mean TRF length in the highest quartile (odds ratio 2.30, 95% Confidence Interval 1.28-4.13, P=0.005).Our data show that patients with AAA have shorter leukocyte telomere length compared to controls. This suggests that vascular biological aging may have a role in the pathogenesis of AAA.