Background: This study aims to compare the mid-term clinical and echocardiographic outcomes of quadrangular resection (QR) and butterfly resection (BR) techniques in patients with isolated posterior leaflet prolapse and/or chordal rupture due to Barlow’s disease. Methods: Between May 2009 and January 2023, a total of 142 patients (89 males, 53 females; mean age: 56.6±11.9 years; range, 20 to 84 years) who underwent mitral valve repair with either QR (n=69) or BR (n=73) were retrospectively analyzed. Patients were evaluated using transthoracic and transesophageal echocardiography preoperatively, intraoperatively, and during mid-term follow-up. Clinical variables, echocardiographic parameters, and surgical data were compared between groups. Results: Baseline characteristics and preoperative echocardiographic findings were similar between the two groups. Both techniques resulted in significant improvements in the New York Heart Association functional class, mitral regurgitation severity, and left ventricular dimensions. However, the BR group demonstrated significantly improved posterior leaflet mobility (Wilkins score 1.97±0.74 vs. 3.23±0.79; p<0.001) and lower mean mitral valve gradient (3 [range, 2 to 4] vs. 6 [range, 5 to 7] mmHg; p<0.001). Coaptation depth was also significantly reduced in the BR group, indicating a more annular-level coaptation. Conclusion: Butterfly resection is a technically feasible, effective, and anatomically favorable technique for mitral valve repair in Barlow’s disease. Its ability to preserve leaflet mobility and minimize mitral gradients makes it a valuable addition to the surgical armamentarium, particularly in anatomically complex cases.