Objeetive We sought to compare the safety and efficacy of cut-and-sew Cox-maze Ⅲ procedure for atrial fi brillation associated with degenerative mitral regurgitation,by comparing with patients without atrial fibrillation.Methods From May 2013 to November 2015,217 patients underwent mitral valve repair were enrolled,including 145 without atrial fibrillation(control group) and 28 received concomitant cut-and-sew Cox-maze Ⅲ procedure (treatment group).Propensity scores were calculated on the basis of 16 known preoperative factors and yielded the best matched patients.Safety and outcomes were compared between the two matched groups.Results 28 pairs of patients were matched successfully.No hospital deaths occurred and the major complications showed no statistical differences (P ＞ 0.05).Cardiopulmonary bypass time and crossclamp time,proportion of amiodarone use and temporary pacemaker use,and postoperative hospital stay in the treatment group were higher than those in the control group(P ＜0.001).Patients were followed up from 6 months to 3 years,and no patients occurred deaths and strokes.After 6 months,there were no significant differences in the rates of sinus rhythm and drug free between the two groups (P ＞ 0.05).In both groups,left atrial diameter and left ventricular diameter decreased,and ejection fraction increased compared with those before operation.Atrial function in the treatment group recovered 3 years after operation.At the latest follow-up,patients in both groups were all at NYHA functional class Ⅰ.Conclusion The additional cut-and-sew Cox-maze Ⅲ procedure for treatment of degenerative mitral disease complicated by atrial fibrillation does not increase the operative risks of mitral valve repair,and had early and mid-term outcomes similar to that of patients without atrial fibrillation.