Background and Objectives: The aim of this study was to investigate the fates of moderate to severe functional tricuspid regurgitation (TR) in patients who underwent mitral valve surgery according to the treatment modalities. Methods: Among 237 patients who underwent mitral valve surgery, 50 patients (50.5짹11.3 years old, 32 females) with moderate to severe functional TR were enrolled and divided into two groups according to the treatment modalities: group I (TV surgery group: 35 patients, 52.2짹9.9 years old, 22 females), group II (Medical treatment group: 15 patients, 46.2짹16.5 years old, 10 females). Changes of the degree of TR and clinical events were analyzed between the groups. Results: Baseline clinical and echocardiographic variables were not different between the groups. The degree of TR was also not different between the groups (3.2짹0.4 in group I vs 3.3짹0.5 in group II, p=0.288). On follow-up echocardiography, the degree of TR were significantly improved in both groups (group I: 3.2짹0.4 to 1.5짹0.9, p<0.001, group II: 3.3짹0.5 to 1.6짹0.6, p<0.001) following treatment. However, the degree of TR was not different between the groups during post-operative follow-up period (1.5짹0.9 in group I vs 1.6짹0.6 in group II, p=0.961). Clinical events during follow-up period were not different between the groups. Conclusion Our results demonstrated that moderate to severe functional TR in patients who underwent valve surgery significantly improved irrespective of treatment modality. TV repair in patients with functional TR should be considered seriously with strict indications.