To better understand late outcomes of mitral valve repair, we reviewed the cases of 49 consecutive patients who underwent reoperation between January 1974 and May 1992 for recurrent valve dysfunction after previous valvuloplasty for mitral regurgitation. There were 27 men (55%) and 22 women, with a median age of 63 years (range 20 to 84 years). Original procedures included annuloplasty and posterior leaflet repair in 15 patients (31%), annuloplasty and anterior leaflet repair in 15 (31%), commissural plication in 13 (27%), and complex bileaflet repairs in six (12%). Median time between initial mitral repair and reoperation was 2.4 years (range 2 months to 25.3 years). Indications for reoperation included recurrent severe mitral regurgitation in 34 patients (70%), hemolytic anemia from mitral regurgitation in seven (14%), mixed mitral regurgitation and stenosis in seven (14%), and isolated mitral stenosis in one (2%). Before reoperation, 36 patients were in New York Heart Association functional class III and 11 were in class IV. Initial repairs were intact at the second operation in 32 patients (65%), and the etiology of recurrent mitral regurgitation in these patients was fibrosis or calcification of the anulus or leaflets in 22 patients, newly ruptured chordae in seven, and perforated leaflets in three. The causes of mitral regurgitation in the 17 patients whose initial repair had failed included dehiscence of commissural repairs in nine patients, dehiscence of ring annuloplasty in four, and break-down of chordal or leaflet repair in four. Patients with original repairs involving the anterior leaflet had a significantly shorter time between operations (p = 0.006). In eight patients (16%), the mitral valve was repaired again; in the remaining 41 patients (84%), prosthetic replacement was performed. Operative mortality rate was 4% (two patients). All eight patients who underwent mitral valve rerepair had no mitral regurgitation, trivial regurgitation, or mild regurgitation at discharge from the hospital. Follow-up was 100% complete at a mean of 5.1 years (range 1 to 19 years). Forty-one patients (87% were in New York Heart Association functional class I or II, and survival at 5 years was 75.3%. Of the eight patients who underwent a second repair, seven had no regurgitation, trivial regurgitation, or mild regurgitation at a median of 4 years' follow-up. The low mortality associated with reoperation supports an aggressive approach toward mitral regurgitation with initial repair. A second repair can be performed in selected patients with durable results at 4 years.