Surgical ablation of atrial fibrillation has gained widespread acceptance, particularly in patients having concomitant cardiac surgery. Today, surgeons can choose from a variety of ablation technologies to facilitate operations intended to treat atrial fibrillation. Evidence suggests that virtually all of the available energy sources are effective at creating lines of conduction block on the arrested heart. However, there is controversy surrounding the choice of lesion set when these new devices are used. The purpose of this review is to address the critical question of lesion set by detailed consideration of contemporary data focusing on the (1) pathogenesis of atrial fibrillation, (2) results of catheter ablation, and (3) results of surgical ablation.