We retrospectively reviewed 128 consecutive patients who underwent quadrangular resection of a prolapsed posterior mitral leaflet and local suture annuloplasty. The median age was 68.1 ± 10.0 years (range, 30-84 years) and 63.3% were male. Mean left ventricular ejection fraction was 63.8% ± 10.2% (range, 25%-80%). The etiology of mitral regurgitation was fibroelastic degeneration in 94 (73.4%) patients, myxomatous degeneration in 26 (20.3%), myxomatous infective endocarditis in 7 (5.5%), and post-infarction papillary rupture in one. There was 1 (0.8%) hospital death. The median follow-up was 4.7 ± 4.7 years (range, 0.01-18.29 years). The freedom from reoperation was 98%, 94%, 87%, and 79% at 1, 5, 10, and 15 years, respectively, improving for the most recent 107 patients, subsequent to technical modification, to: 100%, 96%, 94%, and 90% at 1, 5, 10, and 14 years, respectively. Ten- and 15-year freedom from severe mitral regurgitation was 91%, and 88%, respectively. The overall actuarial 1-, 5-, 10-, and 15-year survival rates were 98%, 90%, 70%, and 52%, respectively, similar to that of the age- and sex-matched United Kingdom population. The long-term results of this technique in selected patients with prolapsed posterior leaflet were considered acceptable.