Aim of the study: The aim of this study was to determine the clinical and echocardiographic predictors of recurrent mitral regurgitation after undersized ring implantation for ischemic mitral regurgitation (MR). Recurrent MR occurs in up to 30% of patients after undersized ring implantation. Understanding the causes of recurrent MR should improve the results of this kind of surgery. Material and methods: The pre- and postoperative echocardiograms of 134 patients operated on for ischemic mitral regurgitation using ring implantation were analyzed. The median follow-up period was 13 months. Results: The strongest influence on MR recurrence was exerted by coaptation length (OR 0.022; p = 0.001), effective regurgitant orifice area (EROA) (OR 1.85; p < 0.002), and vena contracta measured preoperatively (OR 1.42; p = 0.007). The independent predictors of recurrent MR included: the postoperative length of leaflet coaptation, preoperative left ventricular ejection fraction, the severity of regurgitation, and body surface area (BSA). The coaptation length cut-off value of < 6.2 mm was associated with 94% sensitivity and 85% specificity in the prediction of recurrent MR. Conclusions: This study showed that the recurrence of MR after undersized mitral ring implantation is low. The measure of coaptation length is superior to other echocardiographic parameters in the prediction of MR recurrence. Our model of risk stratification may predict mitral valve repair failure after restrictive annuloplasty.