The optimal technique for repairing posterior mitral valve (MV) leaflet (PMVL) prolapse remains undetermined. We aimed to compare leaflet resection and neo-chordae implantation in patients undergoing MV repair for posterior leaflet prolapse, focusing on trans-mitral pressure gradient (PG) and recurrence of mitral regurgitation (MR). We enrolled patients undergoing MV repair using either leaflet resection or neo-chordae implantation for single-segment prolapse of PMVL between 2000 and 2021 at our institution. Longitudinal outcomes were evaluated after adjustments with inverse-probability-of-treatment weighting (IPTW). Repeat echocardiographic measurements (n=3,473, 5.4/patient) of trans-mitral PG and significant (moderate or severe) MR recurrence were estimated using nonlinear mixed-effect models. Subgroup analyses were conducted based on the size and type of prosthesis. Among 639 patients, leaflet resection was used in 479 (75.0%) and neo-chordae implantation in 160 (25.0%). In the IPTW-adjusted cohort, the risk of death (P=0.623) and MV reoperation (P=0.340) did not significantly differ between the two groups during a median follow-up of 97.3 months. Echocardiographic data showed comparable mean (at 5 years, 3.8 vs. 4.0 mmHg; P=0.442) and peak (9.6 vs. 10.4mmHg; P=0.131) PGs between groups, which persisted in most subgroup analyses. However, neo-chordae implantation was associated with a higher probability of significant MR recurrence compared to leaflet resection (at 5 years, 16.1% vs. 7.0%; P<0.001). Leaflet resection yielded similar clinical outcomes and trans-mitral PGs compared to neo-chordae implantation after MV repair, with a lower MR recurrence rate. These findings underscore the need to reassess the efficacy of neo-chordae implantation relative to leaflet resection.