Autoimmunity appears to play a role in abdominal aortic aneurysm (AAA) pathology. Although the chemokine CCL20 has been involved in autoimmune diseases, its relationship with the pathogenesis of AAA is unclear. We investigated CCL20 expression in AAA and evaluated it as a potential biomarker for AAA. CCL20 was measured in plasma of AAA patients (n = 96), atherosclerotic disease (AD) patients (n = 28) and controls (n = 45). AAA presence was associated with higher plasma levels of CCL20 after adjustments for confounders in the linear regression analysis. Diagnostic performance of plasma CCL20 was assessed by ROC curve analysis, AUC 0.768 (CI:0.678-0.858; p<0.001). Classification and regression tree analysis classified patients into two CCL20 plasma level groups. The high-CCL20 group had a higher number of AAA than the low-CCL20 group (91% vs 54.3%, p< 0.001). mRNA of CCL20 and its receptor CCR6 were higher in AAA (n = 89) than in control aortas (n = 17, p<0.001). A positive correlation was found between both mRNA in controls (R = 0674; p = 0.003), but not in AAA. Immunohistochemistry showed that CCR6 and CCL20 colocalized in the media and endothelial cells. Infiltrating leukocytes immunostained for both proteins but only colocalized in some of them. Our data shows that CCL20 is increased in AAA and circulating CCL20 is a high sensitive biomarker of AAA.