This study describes the technique of triangular plication in patients with mitral valve incompetence that is due to segmental anterior leaflet prolapse. A nonabsorbable suture plicates the prolapsed leaflet area towards the ventricular aspect in a triangular fashion by decreasing the suture width towards the leaflet base. Because no leaflet tissue is resected, this technique allows for the intraoperative correction of an imperfect plication. Triangular plication was successful in all except one patient. In this patient, a failed repair was corrected with mitral valve replacement. Freedom from mitral valve incompetence of more than grade 0-I was 100% at 12 months and 86% at 36 months postoperatively.