International guidelines currently recommend concomitant surgical ablation of atrial fibrillation (AF) in patients with AF undergoing cardiac surgery. However, a systematic review and meta-analysis of 23 randomized controlled trials (RCTs) showed no significant difference in mortality or stroke in patients who underwent surgical AF ablation compared with those who did not (moderate-quality evidence). We estimated the Ontario-wide costs of surgical AF ablation between 2006 and 2017 using data from a systematic review and meta-analysis of RCTs, estimates of case volumes from Ontario Health Insurance Plan fee codes, the ongoing left atrial appendage occlusion study III trial (NCT01561651), institutional costs from large academic centers in Ontario, as well as professional fees based on the Ontario fee schedule. Device costs were obtained from Canadian industry data with expert input. We estimated the average extra cost of surgical AF ablation at $4,287 CAD (95% CI $4,113-4,619) per patient. Procedural costs (equipment costs and physician remuneration) comprise 82.2% of this, while smaller portions relate to the increased need for pacemaker (3.9%) and additional hospital length of stay (13.9%). Approximately 2,391 patients underwent surgical AF ablation between 2006 and 2017, corresponding to an estimated $10.2 million in incremental cost during that time span. Ontario taxpayers spend significant financial resources on surgical ablation of AF, a procedure lacking high-quality evidence demonstrating benefit in reducing mortality or stroke. Further large prospective studies examining clinically important outcomes are needed to justify its routine use in patient care and to guide allocation of healthcare funds. © 2020 Wiley Periodicals LLC.