From March 1994 to December 1999, polytetrafluoroethylene suture was used for chordal replacement during mitral valve repair in 30 patients. Follow-up ranged from 4 to 70 months with a mean of 36.6 months and was complete in 29 patients: 14 males and 15 females with a mean age of 40.6 years. Most (17) had rheumatic heart disease, 5 had degenerative disease, 6 had infective endocarditis, and 1 had ischemic heart disease. Preoperatively, 26 patients were in functional class III and IV. Operations comprised isolated mitral valve repair (15), combined mitral and tricuspid valve repair (4), mitral valve repair and aortic valve replacement (3), and others (7). The most frequent additional procedures were commissurotomy, papillotomy, resection of primary or secondary chordae, and chordal splitting. The mean cardiopulmonary bypass and aortic crossclamp times were 155.3 and 120.5 minutes, respectively. There was no hospital mortality. One patient died 20 months postoperatively from chronic obstructive lung disease. All survivors were in functional class I and II. Mitral regurgitation was reduced from a preoperative mean of +3.1 degrees to +0.43 degrees. No thromboembolic event or valve failure occurred during follow-up. It was concluded that polytetrafluoroethylene suture was safe and effective for mitral valve repair.