Background: There has been growing attention for the development of functional tricuspid regurgitation (TR) long after left-sided valve surgery. We attempted to determine the long-term hemodynamic effects of corrective surgery for severe functional TR in patients who had prior left-sided valve surgery using cardiac magnetic resonance imaging (CMR). Methods and Results: 29 patients with severe functional TR were analyzed. CMR was performed within 1 month before and at a median 27.5 months after surgery. Long after TR surgery, 26 patients had no or mild residual TR, 2 had mild to moderate TR, and 1 showed moderate TR. Remarkable reductions in the right ventricular end-diastolic volume index (RV-EDVI) (177.9짹60.0 vs. 118.3짹32.3 mL/m2, P<0.001) and end-systolic volume index (RV-ESVI) (88.3짹30.9 vs. 67.5짹31.0 mL/m2, P=0.003) were observed, whereas RVEF showed no change (50.0짹8.5% vs. 44.9짹12.8%, P=0.09). Preoperative RV-EDVI (R=-0.85, P<0.001) and RV-ESVI (R=-0.55, P=0.002) were significantly associated with their respective changes after corrective surgery. Post-surgery, a normal RVEF was achieved in 25 patients (86.2%). A significant rise in the left ventricular (LV) EDVI (from 92.0짹23.0 to 124.3짹32.3 mL/m2, P<0.001)and cardiac index (CI) was found after surgery (from 3.8짹1.3 to 4.1짹0.8 L/min/m2, P=0.03). Functional capacity as assessed by NYHA class showed a significant improvement from 2.8짹0.6 before surgery to 2.0짹0.6 long after surgery (P<0.001). Conclusion: CMR demonstrated remarkable improvement in RV volumes and the achievement of a normal RVEF after corrective surgery in a majority of patients with functional severe TR. In addition, successful TR surgery leads to a significant rise in LV volumes and CI, which may contribute to significant amelioration in functional capacity of the patients.