Abstract Background As atrial fibrillation (AF) ablation procedures become increasingly prevalent, understanding the risks of procedure-related complications is crucial, particularly in the very elderly population, defined in this context as patients aged 80 years and above. This study aimed to identify risk factors for complications in this demographic. Methods We conducted a prospective analysis of 170,017 AF ablation procedures from the Japan Ablation Registry, covering 482 facilities between 2017 and 2020. The analysis focused on patients aged 80 or older (very elderly group, n=14,389). Multivariate analysis was employed to identify risk factors for procedure-related complications in the very elderly, incorporating factors that showed a p-value of less than 0.1 in univariate analysis. Results Procedure-related complications were observed in 3.62% of the very elderly group. The multivariate analysis (Model 1) identified significant risk factors were the initial procedure (OR 1.30, 95% CI 1.01-1.67, p=0.041), type of AF (OR 1.34, 95% CI 1.03-1.74), and body weight (OR 0.99, 95% CI 0.98-1.00, p=0.082). For further analysis, the type of AF was categorized into paroxysmal AF (PAF), persistent AF (PeAF) and long-standing PeAF. We included these categories, along with the initial procedure and body weight, into further multivariate analysis (Model 2), which revealed that long-standing PeAF (OR 1.34, 95% CI 1.03-1.74, p=0.032), initial ablation (OR 1.30, 95% CI 1.01-1.67, p=0.042) and body weight (OR 0.99, 95% CI 0.98-0.99, p=0.001) were independently and significantly associated with complications. Conclusion This study identifies initial procedures, low body weight, and long-standing PeAF as significant risk factors for procedure-related complications in very elderly patients undergoing AF ablation. These findings highlight the importance of careful patient selection and tailored procedure planning for these subgroups in the very elderly population.