OBJECTIVES: The impact of coaptation length on recurrent mitral regurgitation following degenerative mitral repair is not fully understood. METHODS: Between May 2008 and February 2021, 386 consecutive patients underwent mitral repair for degenerative mitral regurgitation at a single centre. We compared patients with a post-repair coaptation length >11 mm (long-coaptation group, n = 230) and ≤11 mm (short-coaptation group, n = 156). The coaptation length cutoff was selected based on published postoperative transesophageal echocardiographic measurement of mitral repair patients and healthy controls. Propensity score with inverse probability of treatment weighting (IPTW) analyses were performed. The median duration of clinical follow-up was 41 months and follow-up was complete in the entire cohort. RESULTS: The long-coaptation patients underwent more neochord implantation (89% vs 65%, P < 0.001) and less leaflet resection (11% vs 29%, P < 0.001). Overall in-hospital/30-day mortality and mitral reintervention occurred in 3 (1%) and 4 (1%) patients, respectively, and freedom from recurrent mitral regurgitation was 98% at 1 year and 94% at 5 years. Freedom from recurrent mitral regurgitation moderate or greater was significantly higher in the long-coaptation patients (IPTW-adjusted difference in average time to recurrent mitral regurgitation: 31 months, 95% confidence interval 9-53, P = 0.006). However, there was no difference in intermediate-term survival between both groups (IPTW-adjusted difference in average time to death: 9.5 months, 95% confidence interval -27 to 46, P = 0.61). Stratified analysis and pairwise comparison of different coaptation intervals also appeared to support the protective effect of longer coaptation on repair durability. CONCLUSIONS: Longer coaptation length appears to be associated with improved intermediate-term durability after mitral repair.