Aim: The aim of this study was to evaluate whether ranging values of thiol and disulphide herald a dilatation or impending acute aortic syndrome at thoracic aorta. Results/methodology: Study population consisted of patients with aortic aneurysm (n = 58), with acute aortic syndrome (n = 32) and without aortic aneurysm (control group; n = 61). A spectrophotometric method was used to determine thiol and disulphide. Native and total thiol levels were moderately correlated with maximal aortic diameter. At the end of 6 months, there was statistically significant increase in native, total thiol levels and decrease in disulfide and disulphide/native thiol ratio in operated group. Discussion/conclusion: Lower thiol levels may be associated with the higher risk of aortic aneurysm development and may increase after surgical therapy.