The relationship between bilirubin levels and peripheral artery disease has been documented. Our aim was to demonstrate the possible relationship between serum bilirubin levels and abdominal aortic aneurysms (AAAs). The study included 219 patients, 110 had a previous diagnosis of AAA and 109 patients were normal controls. Only patients with AAAs which had a size of 40 to 54 mm were included in the study. Baseline laboratory values and 2 computerized tomographic measurements 12 months apart were recorded. Patients with AAA had significantly higher white blood cell (WBC) counts and neutrophil–lymphocyte ratio (NLR) but lower total and direct bilirubin levels compared with the control patients (P < .05). Multivariate logistic regression analysis showed that WBC, NLR, and total and direct bilirubin levels were independent predictors of the presence of an AAA (P = .03, P = .001, P = .001, and P = .001, respectively). White blood cells and total bilirubin level were independent predictors of a rapidly enlarging AAA (>10 mm/y, P = .002 and P < .001, respectively). This study demonstrated that increased WBC and decreased total bilirubin levels were independent predictors of an AAA, especially the subgroup in which the AAA was rapidly expanding.