BACKGROUND: This study aimed to elucidate the distinctions between the expression levels of angiotensin-converting enzyme (ACE) and ACE2, as well as their genetic polymorphisms, in patients with acute aortic dissection (AD) and coronary heart disease (CHD). METHODS: A cohort of 86 patients was enrolled, comprising 34 individuals with acute AD (encompassing Stanford types A and B), 18 with ascending aortic aneurysm, 21 with CHD, and 13 healthy controls. Aortic tissue samples were procured from 44 patients during surgical interventions. RESULTS: Statistically significant differences were observed in ACE and ACE2 expression levels among the ascending aortic aneurysm, CHD, and control groups ( CONCLUSION: Plasma ACE levels, and the gene expressions of ACE and ACE2, are markedly reduced in patients with acute AD. The observed imbalance in ACE and ACE2 expressions may play a pivotal role in the pathogenesis of AD.