Aim To assess the outcome and cost of catheter ablation of atrial fibrillation (AF) in Belgium. Methods and results From a nationwide health insurers' database, we retrieved claims data of all patients that underwent a catheter ablation of AF from November 2007 through December 2008. Based on data on reimbursed procedures and drugs, we assessed AF recurrence using different models. Costs related to the index hospitalization were calculated. During the observation period, 830 patients underwent a first catheter ablation of AF. Two-year follow-up data were available for all patients, with an average follow-up of 30.2 months. Seventy-seven percent of patients were treated for paroxysmal AF. Recurrence of AF was defined as the occurrence of one of the following events: a repeat catheter ablation, an electric cardioversion or an antiarrhythmic drug (AAD) prescription, the latter two taking into account a blanking period of 3 months. Atrial fibrillation recurred in 59.8% of patients after 1 year and in 65.9% of them after 2 years. If AAD prescription was considered as an indicator for ablation failure only if it occurred after a 1 month AAD-free period, recurrence of AF occurred in 37.3% of patients after 1 year and in 49.9% after 2 years. Based on the prescription of rate and rhythm control drugs before the ablation, we conclude that up to 15.8% of patients underwent catheter ablation as first-line therapy. Catheter ablation of AF in Belgium on average costs about €9600 for the initial intervention. Conclusion Since the effectiveness of catheter ablation of AF appears to be less favourable in real-world practice as compared with results reported in clinical trials, and given the high initial cost of the procedure, we suggest to strictly limiting the intervention to patients in whom it is currently believed to be most beneficial, i.e. those with severely symptomatic and drug-refractory paroxysmal AF with no or minimal structural heart disease.