A 65-year-old man with degenerative mitral valve disease had mitral valve repair consisting of posterior leaflet resection and leaflet repair with polypropylene suture and annuloplasty. Six years later, he presented with recurrent mitral regurgitation. The cut tail of a polypropylene suture used at the initial repair had eroded the free edge of the anterior leaflet and its chordae. Chordal transfer was used to re-repair the valve. Soft, braided suture is preferred for leaflet approximation at mitral valve repair; if polypropylene suture is used, suture tails and knots should be positioned such that they do not come into contact with leaflet tissue.