© 2021 Ankara Yildirim Beyazit University.Objectives: To study changes in dynamic thiol/disulfide homeostasis (TDH) in patients with acute aortic dissection (AAD). Materials and Methods: In our study, the medical records of patients who applied to Ankara Atatürk Training and Research Hospital between January 2015- January 2018 and were found to have AAD on computed tomography of the thorax were retrospectively reviewed. There were two groups in the study, one AAD group, and the other healthy volunteers' group. First, thiol and disulfide levels were determined with the spectrophotometric method defined by Erel and Neşelioğlu, natural thiol (NT), total thiol (TT), and disulfide (D) levels, and their ratios were calculated (index 1: D / NT, index 2: D / TT, index 3: NT / TT). We compared these two groups in terms of Oxidative stress parameters. Results: A total of 40 patients with AAD and 38 age-matched healthy volunteers were included in this study. There was no significant difference between the two groups in terms of gender and age (p=0.923, p=0.401, respectively). The AAD group had significantly lower natural thiol and total thiol (p<0.001), but disulfide levels were similar (p=0.360). Oxidative stress parameters were not statistically significant in terms of mortality. Conclusion: We found significantly lower thiol/disulfide homeostasis in patients with AAD, particularly native thiol and total thiol. We think that oxidative stress theory may play a role in the pathophysiology of AAD and oxidative stress parameters may guide the diagnosis.