Objective    To evaluate the effects of modified MAZE procedure using bipolar irrigated radiofrequency ablation for treating atrial fibrillation.     Methods    A retrospective analysis was carried out for 100 cases with rheumatic heart disease and atrial fibrillation (38 males and 68 females

at a mean age of 45.2) from March 2006 to December 2009 in our department. This cohort underwent cardiac valve replacement and modified MAZE procedure using irrigated radiofrequency ablation during concomitant open heart surgeries. Preoperative records of electrocardiogram and echocardiogram and those postoperative records in 3 and 6 months after surgery were compared to determine the efficacy of the surgery.     Results    There were 91 patients with sinus arrhythmia (91.0%)

8 patients with junctional rhythm (8.0%)

and 1 patient with atrial fibrillation (1.0%)  just after the operation. Three patients were dead of severe heart and lung  failure during the perioperative period. In 6 months after surgery

there were 80 cases of sinus arrhythmia (80/97

82.5%)

17 cases of junctional rhythm (17/97

17.5%)

and none case of atrial fibrillation. There was no Ⅲ  atrioventricular block. No patients needed the secondary thoracotomy surgery because of hemorrhage.     Conclusion    The modified MAZE procedure using irrigated radiofrequency is an effective method to treat atrial fibrillation.