Background: Current guidelines recommend stopping oral anticoagulation and starting bridging anticoagulation with intravenous heparin or subcutaneous enoxaparin when implanting a pacemaker or defibrillator in patients at moderate or high risk for thromboembolic events. A limited body of literature suggests that device surgery without cessation of oral anticoagulation may be feasible. Objective: The purpose of this study was to evaluate the safety of device surgery in orally anticoagulated patients without interrupting warfarin therapy. Methods: We performed a retrospective study of 459 consecutive patients on chronic warfarin therapy who underwent device surgery from April 2004 to September 2008. Warfarin was continued in 222 patients during the perioperative period. Warfarin was temporarily held and bridging therapy administered in 123 patients. Warfarin was temporarily held without bridging therapy in 114 patients. Results: There were no significant differences with regard to age, sex, or risk factors for thromboembolism in the three groups. Patients who continued taking warfarin had a lower incidence of pocket hematoma (P = .004) and a shorter hospital stay (P <.0001) than did patients in the bridging group. Holding warfarin without bridging is associated with a higher incidence of transient ischemic attacks (P = .01). Conclusion: Temporarily interrupting anticoagulation is associated with increased thromboembolic events, whereas cessation of warfarin with bridging anticoagulation is associated with a higher rate of pocket hematoma and a longer hospital stay. Continuing warfarin with a therapeutic international normalized ratio appears to be a safe and cost-effective approach when implanting a pacemaker or defibrillator in patients with moderate to high thromboembolic risk.