Abstract: Objective To summarize the experiences of radiofrequency modified maze procedure for atrial fibrillation (AF) in patients with mitral valve diseases. Methods From May 2003 to December 2008, 122 patients, including 31 males and 91 females, with permanent AF underwent radiofrequency modified maze procedure as a combined operation with mitral valve replacement. Their age ranged from 23 to 65 years old (47±10 years). The duration of AF varied from 0.5 to 32.0 years (6.5±5.7 years). There were 57 cases of stenosis, 7 cases of regurgitation and 58 cases of both stenosis and regurgitation. Ablation lines were made with Cardioblate (Medtronic, monopolar, 25.30 W, 180.240 ml/h). After rightsided maze procedure was finished, aorta was crossclamped and cold crystalloid or blood cardioplegia were delivered for myocardial protection. Left atrial incision was performed through the interatrial groove or interatrial septum. The ablation lines were created to encircle the orifices of the left and right pulmonary veins respectively. The ablation lines were also performed from the left encircling line to the posterior mitral valve annulus and to the orifice of left atrial appendage respectively. An ablation line was used to connect the circumferential line of left and right pulmonary veins. The left atrial appendage was tied and concomitant operations were performed. Amiodarone was given to the patients after operation and regular follow-up was done. Results There were four perioperative deaths including 2 cases of multiple organ failure, 1 case of mechanic valve obstruction and 1 sudden death. Follow-up was done to 115 patients for 1.5-7.0 years (4.8±2.6 years) with three cases lost. During the followup period, four patients died, including 3 sudden deaths and 1 case of prosthetic obstruction. Eightyseven patients (78.4%, 87/111) recovered to sinus rhythm; 22 patients still had AF; 1 patient had atrial flutter; and 1 patient required a permanent pacemaker one year after the operation. Diameter of left atrium after operation (0.5-7.0 years) was decreased compared with that before operation（44.90±7.50 mm vs. 54.30±10.80 mm，t＝10.641，P＝0.000）. Conclution Radiofrequency modified maze procedure for AF in patients with mitral valve disease is relatively safe. But heart rhythm instability, tachyarrhythmia and recurrent AF are not rare for those patients. Therefore, the surgical indication of AF should be individualized.