This study determined the efficacy of single- and multisite atrial pacing for terminating episodes of atrial fibrillation induced in patients in the electrophysiology laboratory. One- to 5-second bursts of atrial pacing at a cycle length of 20 ms were not effective in terminating atrial fibrillation, when delivered either in the high right atrium or when delivered simultaneously at the high right atrium, midseptum, and coronary sinus.