Abstract: Objective To observe the longterm condition of patients after mitral valve replacement with or without mild aortic valve regurgitation (AR) and discuss whether treatment of AR is necessary during the course of mitral valve replacement. Methods From March 1999 to April 2004, 88 patients who underwent mitral valve replacement (with or without mild AR before surgery) in West China Hospital of Sichuan University were followed up for 5 years or more. The patients were divided into two groups according to whether they had mild AR based on the result of preoperative echocardiography examination. In the AR group, there were 35 patients including 7 males and 28 females aged 49.26±11.87. By the New York Heart Association (NYHA) grading system before surgery, 4 patients were classified as Class Ⅱ, 26 Class Ⅲ and 5 Class Ⅳ. In the nonAR group, there were 53 patients including 7 males and 46 females aged 48.59±10.22. Using the NYHA grading system before surgery, we found there were 7 patients with Class Ⅱ cardiac function, 39 Class Ⅲ and 7 Class Ⅳ. After operation, all patients were followed up regularly and 5 years after surgery, patients were examined by echocardiography again. Results The followup period ranged from 5 to 9 years (6.39±1.26). There was no statistical difference in gender (P=0.394), age (P=0.841), preoperative cardiac function (P=0.960) and cardiac rhythm (P=0.732) between the two groups. For the AR group, after operation, NYHA heart function, left ventricle ejection fraction (LVEF) and left ventricle fraction shortening (LVFS) significantly increased or improved(Plt;0.05). In the nonAR group, after operation, NYHA heart function and LVEF significantly improved (Plt;0.05), while LVFS had no significant change (Pgt;0.05). Left [CM(159mm]ventricular dimensions (LVD) and aortic dimensions between the two groups had no significant difference afteroperation (Pgt;0.05). There was no significant difference in the number of AR cases before and after surgery (Pgt;005) in the AR group, while there was a significant difference in the nonAR group (Plt;0.05). Conclusion For patients with mild AR who underwent mitral valve surgery 5 to 9 years ago, there is little change in their AR condition. There is no need to treat mild AR preventively during the course of mitral valve replacement.