Abstract OBJECTIVES To compare the early- and long-term clinical outcomes of concomitant surgical ablation (SA) for atrial fibrillation (AF) during isolated aortic valve replacement (AVR) using data from the Korean National Health Insurance Service Database. METHODS Of 23,332 adult patients who underwent AVR between 2003 and 2019, those with underlying AF with or without concomitant SA were extracted, and propensity score matching analysis was performed. RESULTS Overall, 1,741 patients with underlying AF with (n = 445, group A) or without (n = 1,296, group N) concomitant SA during isolated AVR were enrolled, from whom 435 pairs were matched in a 1:1 ratio using propensity score matching analysis. The operative mortality and early postoperative morbidities, including bleeding reoperation, stroke, permanent pacemaker implantation and acute kidney injury were comparable between the groups. The overall survival showed no differences between the groups. However, the cumulative incidence of new-onset late ischaemic stroke was significantly lower in group A than group N in propensity score-matched patients [2.3 vs 3.5 per 100 patient-years, adjusted hazard ratio (95% confidence interval) 0.64 (0.43–0.96), Group A versus Group N, respectively]. The cumulative incidence of other morbidities such as reoperation, permanent pacemaker implantation and progression to chronic renal failure showed no difference between groups. CONCLUSIONS The incidence of late ischaemic stroke was significantly lower when concomitant SA was performed during isolated AVR in patients with underlying AF. Therefore, concomitant SA should be actively considered in patients with underlying AF undergoing isolated AVR to prevent the occurrence of late ischaemic stroke.