Abstract: Objective To explore whether clinically mild functional tricuspid regurgitation should be addressed at the time of mitral valve repair (MVP) for moderate or severe mitral regurgitation due to myxomatous degeneration. Methods We retrospectively analyzed the outcomes of 135 patients with moderate or severemitral regurgitation due to myxomatous degeneration with mild functional tricuspid regurgitation. All patients were treated between January 1993 and March 2008 in the Department of Cardiothoracic Surgery of Changhai Hospital, the Second Military Medical University. We divided the patients into a MVP group (n=76) and a MVP+tricuspid valvuloplasty (TVP) group(n=59) according to whether they underwent combined TVP, and observed the perioperative mortality rate, degree of tricuspid regurgitation, and compared survival rate, and freedom from longterm moderate or severe tricuspid regurgitation after operation. Cox regression was used to analyzethe risk factors for longterm moderate or severe tricuspid regurgitation after operations. Results (1) There were no deaths during the perioperative period, and postoperative transthoracic echocardiography of all patients indicated that tricuspid regurgitation was mild or less. (2) Survival rate at 5 years, 10 years after operations in MVP group was 98.4%, 95.0%, respectively, and survival rate at 5 years, 10 years after operations in MVP+TVP group was 100.0%, 93.7%, respectively, and there was no significant difference in the survival rate after operations between the two groups(P=0.311), butthere was a significant difference in the freedom from longterm moderate or severe tricuspid regurgitation after operations between the two groups (P=0.040). Multivariate Cox regression showed that preoperative pulmonary artery pressure gt;30 mm Hg (95%CI 1.127 to 137.487, P=0.040 )and atrial fibrillation (95%CI 1.177 to 23.378, P=0.030) wereindependent risk factors for longterm moderate or severe tricuspid regurgitation afteroperations.Conclusion TVP is necessary for most patients undergoing MVP for moderate or severe mitral regurgitation due to myxomatous degeneration who have coexistent mild functional tricuspid regurgitation, especially those patients with preoperative pulmonary artery pressure gt;30 mm Hg or atrial fibrillation.