Background outpatient direct current (DC) cardioversion is performed routinely, yet scant data support this approach. We studied the efficacy, safety, and costs of outpatient cordioversion. Methods A retrospective analysis of outpatient cardioversions was performed in a 5-year period at an academic medical center in 532 consecutive outpatients with an atrial tachyarrhythmia. The protocol included anticoagulation (international normalized ratio greater than or equal to2.0) for greater than or equal to4 consecutive weekly draws and then DC cardioversion with the patient under intravenous anesthesia. Arrhythmia symptoms, antiarrhythmic therapy use, and costs were evaluated. Results Ninety percent of patients were discharged in sinus rhythm after cardioversion with a median number of shocks of 1 (range, 1-6) for atrial flutter (n = 113), atrial tachycardia (n = 13), and atrial fibrillation (n = 406). Sixty-seven percent of patients were treated with an antiarrhythmic drug. The complication rate was 2.6%, with I I unplanned admissions. Thromboemboli occurred only in patients whose anticoagulation deviated from protocol and included chronic hemianopsia starting 4 day s after cardioversion, transient right-sided weakness, and cerebral vascular accident 3 days after cardioversion, despite negative results on a transesophageal echocardiogram. Two patients had postcardioversion pulmonary edema. Bradycardia developed in 4 patients; transient pacemaker noncapture after the shock occurred in 4 patients. Transient postshock rhythms also included AV nodal Wenckebach and junctional rhythm. One patient had aspiration pneumonia. The-mean cost of cardioversion was $464. Fees for anesthesia ranged from $525 to $650. The anesthetic costs ranged from $2.84 to $21.47. The cardiology fee averaged $501. Conclusion Outpatient cardioversion is a low risk, effective, and economical procedure.