OBJECTIVES: Atrial fibrillation (AF) is a chronic, progressive disease characterized by uncoordinated atrial activation involving a rapid and irregular heartbeat.  Its prevalence has been increasing worldwide.  Antiarrhythmic drug therapy is a commonly-used treatment for paroxysmal AF , and catheter ablation has become an important treatment alternative.  The purpose of this study was to assess the cost-effectiveness of catheter ablation compared to antiarrhythmic drug (AAD) therapy for the treatment of paroxysmal AF in the United Kingdom.  METHODS: A Markov simulation model was developed for a hypothetical cohort of 55-year-old patients with drug-refractory paroxysmal AF and a low stroke risk.  The model treatment arms were catheter ablation and AAD mono-therapy.  The model was created to assess the costs and quality-adjusted life-years over a lifetime horizon.  Clinical efficacy of catheter ablation and AAD therapy were modeled based on the results of a recently published randomized controlled trial (Wilber et al., 2010).  Utilities and other transition probabilities were drawn from the published literature.  Costs were specific to the United Kingdom. RESULTS: The incremental cost-effectiveness ratio for catheter ablation versus AAD therapy ranged from £12,500 to £15,300 per quality-adjusted life-year.  Over a lifetime horizon, the quality-adjusted life expectancy ranged from 11.75 to 12.20 years for catheter ablation compared to 11.00 to 11.35 years for AAD therapy.  Model results were most sensitive to ablation costs, probability of successful ablation treatment, probability of revision to AF, and probability of successful AAD therapy.  CONCLUSIONS: Catheter ablation appears to be cost-effective compared to AAD therapy among patients who had drug refractory paroxysmal AF in the United Kingdom population when using a cost-effectiveness threshold of £20,000.