Atrial fibrillation is by far the most common heart arrhythmia and is even increasing in prevalence and incidence. Approximately 10% of all cardiologic hospitalizations are due to atrial fibrillation. Several studies have shown older patients with paroxysmal or persistent atrial fibrillation and with minor symptoms related to the arrhythmia do equally well on a frequency control as compared to a rhythm control strategy. However, some of this lack of difference in outcome may be because the benefits by achieving sinus rhythm are outbalanced by the risk of medication with presently known antiarrhythmic drugs together with the only modest efficacy of these drugs. Non-pharmacological treatment of atrial fibrillation has drawn increasing interest over the last decade, and especially percutaneous catheter based ablation strategies have been in focus with promising results on the symptomatic level in several series of patients. Different technologies have been in use with very few comparative studies. Most important, no study has been published so far on a consecutive series of patients with atrial fibrillation randomized to either a pharmacological or an ablative strategy. Also important is that the majority of studies have been single-centre based prone to a multitude of potential selection biases.