BACKGROUND Surgical repair of concomitant functional moderate tricuspid valve (TV) regurgitation at the time of mitral valve (MV) surgery remains controversial. OBJECTIVE The objective of this study was to evaluate the outcomes of concomitant repair of functional moderate tricuspid regurgitation (TR) during MV surgery for rheumatic valve disease. METHODS From 1998 to 2016, 1,240 patients had rheumatic MV disease associated with moderate functional TR: 974 patients had MV surgery and concomitant TV repair (group 1) and 266 patients had MV surgery alone (group 2). Study endpoints were operative outcomes, rehospitalisation for congestive heart failure (CHF), and TV reintervention. Propensity score matching identified 192 well-matched pairs for outcomes comparison. RESULTS Patients who had concomitant TV repair were younger (p=0.02) and there were fewer diabetics (p=0.015). In matched patients, low cardiac output was significantly higher in group 2 (p=0.044) and there was no difference in ventilation time, intensive care unit stay, cardiopulmonary bypass, and ischaemic times (p=0.480, p=0.797, p=0.232, and p=0.550, respectively) between groups. Patients in group 2 required more TV reintervention (1 vs 35 in group 1 and 2, respectively; p=0.004) and rehospitalisation for CHF (5 vs 40 in group 1 and 2, respectively; p<0.001). CONCLUSIONS Concomitant TV repair for moderate TR in patients undergoing rheumatic MV surgery was not associated with increased operative risk. Postoperative low cardiac output syndrome and the risk of late TV reinterventions and rehospitalisation for CHF were lower with TV repair. Concomitant repair of the moderate TV regurgitation maybe beneficial for patients undergoing rheumatic MV surgery.