OBJECTIVE The aim of this study was to describe the pattern of lesions responsible for commissural prolapse, the techniques of valve repair and their long-term results. METHODS Between 1992 and 2004, 128 mitral valve repairs were consecutively performed for commissural prolapse. There were 86 males and 42 females, the median age was 57.5 years (range 14-84 years). Forty-six percent of patients were in NYHA III or IV, mean ejection fraction was 61+/-9.4%. The diagnosis of commissural prolapse was recognized by preoperative echocardiography in 32% of the patients and was revealed by intraoperative inspection of the valve in the other cases. The site of the prolapse was the posteriomedial commissure (n=94), the anterior commissure (n=30) or both (n=4). The aetiologies were: infective endocarditis (n=56), degenerative (n=46), ischemic (n=25), congenital mitral regurgitation (n=1). The commissural prolapse was associated with another mitral valvular lesion requiring a specific treatment in 61 cases (47.7%). An associated procedure was carried out in 45 patients. RESULTS The operative treatment of the commissural prolapse included: commissural closure 65 (50.8%), leaflet resection 31 (24.2%), transposition or shortening of chordae 19 (14.8%), reimplantation or shortening of papillary muscles 3 (2.3%), and replacement of the commissural area by a partial mitral homograft 10 (8%). In-hospital mortality included three deaths (2.3%) and four patients (3.1%) were reoperated: three pericardial drainages for hemopericardium and one for mediastinitis. During the follow-up, one patient died (0.8%) from myocardial infarction and eight patients (6.3%) were reoperated including six (4.7%) for recurrent mitral regurgitation. After a median follow-up time of 76.9 months (range from 15 days to 160 months), 116 patients (90.1%) were in NYHA I. Echocardiographs showed no or minimal insufficiency in 112 patients (87.5%) and mild or moderate insufficiency in 10 patients (7.8%). CONCLUSIONS The diagnosis of commissural prolapse is difficult by preoperative echocardiography. The aetiology of the mitral disease is variable (endocarditis, degenerative or ischemic mitral regurgitation). Using a variety of techniques, commissural prolapse can be repaired with excellent clinical and echographic long-term results.