In patients with primary mitral regurgitation (MR), concomitant tricuspid valve (TV) annuloplasty at the time of left-sided valve surgery is indicated in case of a dilated TV annulus ≥40 mm independent of the presence or severity of tricuspid regurgitation (TR). However, the long-term impact on right ventricular (RV) adverse remodeling is less well established and the benefit of preventive TV annuloplasty remains controversial. The aim of the study was to assess differences in long-term RV adverse remodeling and the development of significant TR in those patients. In total, 98 patients (mean age 65 ± 11 years, 85% men) with significant primary MR and TV annulus dilatation ≥40 mm without significant TR who underwent mitral valve (MV) repair with or without concomitant TV annuloplasty were included. Of the 98 patients, 28 patients underwent isolated MV repair without TV annuloplasty and 70 patients received concomitant TV annuloplasty at the time of MV surgery. The RV basal diameter (p = 0.03), RV long-axis diameter (p = 0.04), RV end-diastolic area (p <0.01), and RV end-systolic area (p = 0.03) showed less adverse remodeling at follow-up in patients with concomitant TV annuloplasty compared with patients without TV annuloplasty. Additionally, 4 patients (14%) in the subgroup without TV annuloplasty developed significant TR during follow-up in contrast to zero patients in the subgroup with TV annuloplasty (p = 0.001). In conclusion, concomitant preventive TV annuloplasty during MV surgery in patients with primary MR, no significant TR and a tricuspid annulus (≥40 mm) prevented RV adverse remodeling and the development of significant TR at long-term follow-up.