OBJECTIVES: The role of C-reactive protein (CRP) and interleukin-6 (IL-6) as markers in the prognosis of asymptomatic thoracic aortic aneurysm (TAA) patients has not been well established. As such, we evaluated a group of patients for a possible association between serum CRP and IL-6 and aneurysm dimension.METHODS: Serum CRP and IL-6 were determined and aneurysmal size was measured in 26 patients with TAA.RESULTS: The mean (SD) CRP and IL-6 were 0.58 (1.07) and 7.47 (17.78) pg/ml, respectively. Serum CRP, IL-6 and the ratio CRP/IL-6 correlated with the descending aortic aneurysmal dimension (r = 0.426, r = 0.743 and r = 0.328, respectively). A significant correlation was also found between values of the ratio above 0.8 and aneurysmal dimension (both ascending and descending aneurysms) (r = 0.785). Additionally, a significant association between smoking, age group above 69 years and dyslipidemia and aneurysm dimension was established (P = 0.002, P = 0.061 and P = 0.070, respectively).CONCLUSIONS: This report shows that serum CRP, IL-6 levels and the ratio CRP/IL-6 are associated with descending aortic aneurysmal dimensions. Also values of the ratio CRP/IL-6 above 0.8 are associated with aneurysmal dimensions for both ascending and descending aortic aneurysms. It is still early to establish the clinical significance of those findings, and further studies with larger groups of patients with longer follow-up are required in order to truly assess the usefulness of the serum CRP and IL-6 as markers in relation to the progression of the disease.