BACKGROUND: We aimed to determine the effect of aortic annular enlargement on the midterm outcomes of aortic valve replacement surgery by comparing patients with the same-sized (≤23 mm) native aortic annuli. METHODS: From January 2011 to June 2022, 1328 patients underwent isolated aortic valve replacement-1163 without aortic annular enlargement (AVR group) and 165 with aortic annular enlargement (AVR+AAE group). Propensity score matching identified 112 pairs, controlling for native aortic annulus diameter, age, sex, diabetes, chronic lung disease, dialysis, ejection fraction, prior cardiac surgery, indication, hypertension, dyslipidemia, valve type, prior stroke, prior myocardial infarction, and case status. RESULTS: Demographic and preoperative variables were similar, except body surface area was larger in the AVR+AAE group (2.1 m CONCLUSIONS: Patients with small native aortic annuli (≤23 mm) undergoing isolated aortic valve replacement may benefit from aortic annular enlargement.