Aortic dilatation due to inflammation may lead to an increase in C-reactive protein (CRP) levels. We investigated the possible relationship between CRP-to-albumin ratio (CAR) and presence and progression of abdominal aortic aneurysms (AAAs). The study included 150 patients previously diagnosed with AAA (diameter 40-54 mm) and 100 normal controls. Clinical and laboratory parameters and maximal cross-sectional AAA diameters (measured by computed tomography angiography) were obtained from all participants at baseline assessment as well as after 1 year for those with an AAA. The patients with AAA had significantly higher serum CAR compared with controls at baseline(P< .001). Increased serum CAR was found to be an independent predictor of the presence of AAA (odds ratio: 3.162, 95% CI: 1.690-5.126,P= .001) after multivariate logistic regression analysis. There was a significant increase in aortic diameter and CAR after 1 year in the patients with AAA (P< .001;P= .003); a significant correlation was found between changes in the diameter of AAAs and CAR (r= 0.414;P= .005). Serum CAR may be useful as an inflammatory biomarker for the presence and progression of AAA.