BACKGROUND : The long-term effect of concomitant surgical ablation (SA) on clinical outcomes in an unselected population of patients has not been sufficiently reported in randomized studies. OBJECTIVE : The aim of this study was to assess clinical outcomes of the SA after 5 years of follow-up. METHODS : The PRAGUE-12 study was a prospective, randomized clinical trial assessing cardiac surgery with ablation for AF vs cardiac surgery alone. Patients with AF who were also indicated for cardiac surgery (coronary artery disease [CAD], valve surgery) were randomized to SA or control (no ablation) group. All patients were followed for 5 years. The primary endpoint was a composite of cardiovascular death, stroke, hospitalization for heart failure, or severe bleeding. Secondary endpoint was a recurrence of AF. RESULTS : A total of 207 patients were analyzed (SA group = 108 patients, control group = 99 patients). Both groups were similar relative to important clinical characteristics except for CAD, which was more common in the control group. Cumulative incidence curves showed a higher incidence of the primary endpoint in the control group (P = .024, Gray's test). However, after adjusting for all covariables, the difference between groups was not significant (subhazard ratio [SHR] 0.69 [0.47-1.02], P = .068). The incidence of stroke and AF recurrences were significantly reduced in the SA group, and remained significant even after adjustment for all covariables, including CAD (stroke: SHR 0.32 [0.12-0.84], P = .02, AF recurrences: SHR 0.44 [0.31-0.62], P < .001). CONCLUSIONS : Concomitant SA of AF is associated with a greater likelihood of maintaining sinus rhythm and a decreased risk of stroke.