Reviewing reoperative mitral valve repair, we evaluated a predictor for future reoperation by comparing degenerative and rheumatic mitral regurgitation.From June 1988 to September 2002, 159 patients with mitral valve regurgitation underwent a variety of surgical reconstruction. Our 9 subjects--2 men and 7 women with a mean age of 55.3 years--including 1 undergoing initial repair at an other hospital, underwent reoperation for mitral valve lesions. Four patients had rheumatic (Group R) and 5 degenerative (Group D) mitral valve disease. We studied reoperative outcomes and initial procedures were retrospectively.The mean interval from initial repair was 111 months. Mitral valve lesions at reoperation in Group D were annular dilation in 3, leaflet prolapse in 1, and suture disruption in 1, while that in Group R involved severe thickening of both leafle. Rerepair was possible in 3 patients of Group D, but all others, (including Group R patients) required valve replacement. All survived reoperation.Rerepair in rheumatic mitral regurgitation, rerepair was difficult. In degenerative mitral valve regurgitation, however, rerepair was possible because procedure-related origin was a major cause of reoperation. Reoperation can be prevented by proper technical improvement at initial repair.