Abstract Background: Untreated tricuspid regurgitation during mitral valve surgery may progress to severe symptomatic tricuspid regurgitation. Concomitant repair may increase the operative risk; however, re-operative tricuspid valve surgery is a highrisk procedure. This study's objective was to identify the predictors of DeVega repair failure in patients with functional tricuspid regurgitation and concomitant mitral valve surgery. Methods: This research is a retrospective comparative study that included 140 patients who underwent tricuspid valve repair concomitant with mitral valve replacement. We divided the patients into two groups; the first group (n=106) included patients with no DeVega failure at six-months follow-up (The sustained repair group). The second group included 34 patients who developed moderate or higher TR after the DeVega and was named the failed repair group. Results: The demographic data and comorbidities were not statistically different between both groups. The preoperative atrial fibrillation (73 (69%) vs. 30 (88%)’ p= 0.027) pulmonary artery pressure (64.8±3.6 vs. 81±6.5 mmHg; p= 0.02), right ventricular dimension (4.85±0.24 vs. 5.23±0.37 cm; p= 0.03), and time between the indication of surgery and operation (8.3 ± 3.1 vs. 14.7 ± 5.4 months; p = 0.003) were higher in patients with failed DeVega repair. There was no statistically significant difference regarding the mean bypass time, cross-clamp time, ICU and hospital stay, and postoperative complications between both groups. Predictors of failure after six months were preoperative heart failure (OR: 15.4 (95% CI: 3- 92.3); p= 0.003), long time between diagnosis and surgery (OR: 12.3 (95% CI: 2.1- 84.7); p= 0.007), and postoperative severe pulmonary hypertension (OR: 24.7 (95% CI: 3.1- 199.6); p= 0.003). Conclusions: DeVega repair is associated with a high failure rate after six months. The study of predictors of failure could change our management plans to reach the best results for repair.