OBJECTIVES Mitral valve (MV) annuloplasty ring dehiscence with subsequent recurrent mitral regurgitation represents an unusual but challenging clinical problem. Incidence, localization and outcomes for this complication have not been well defined. METHODS From 1996 to 2016, a total of 3478 patients underwent isolated MV repair with ring annuloplasty at the Leipzig Heart Centre. Of these patients, 57 (1.6%) underwent reoperation due to annuloplasty ring dehiscence. Echocardiographic data, operative and early postoperative characteristics as well as short- and long-term survival rates after MV reoperation were analysed. RESULTS Occurrences of ring dehiscence were acute (<30 days), early (≤1 year) and late (>1 year) in 44%, 33% and 23% of patients, respectively. Localization of annuloplasty ring dehiscence was found most frequently in the P3 segment (68%), followed by the P2 (51%) and the P1 segments (47%). The 30-day mortality rate and 1- and 5-year survival rates after MV reoperation were 2%, 89% and 74%, respectively. During reoperation, MV replacement was performed in 38 (67%) and MV re-repair in 19 (33%) patients. CONCLUSIONS Annuloplasty ring dehiscence is clinically less common, localized more frequently on the posterior annulus and occurs mostly acutely or early after MV repair. MV reoperation can be performed safely in such patients.