Since 1968, the mitral valve was repaired, rather than replaced, in 647 patients. During the same period, 2,223 patients underwent prosthetic mitral replacement. Short and long-term results of mitral repair compare favorably with those after valve replacement. Five-year actuarial survival was 89% after closed commissurotomy (213 patients), 87% after open commissurotomy (203 patients) and 81% after more complex reconstructive procedures (231 patients). The operative risk was below 3% in all groups, the risk of reoperation was between 0.7% and 3%/patient year. Reconstruction was feasible in 16 patients with "floppy valve" syndrome, in 73 patients with ruptured chordae of the posterior leaflet and in 7 patients with bacterial endocarditis, with good long-term results in all of these patients. The feasibility of mitral reconstruction depends on the pliability of the anterior mitral leaflet, which may be decreased in mixed rheumatic lesions. In these patients, we would recommend prosthetic replacement of the valve. It is concluded that superior results may be achieved by mitral repair as compared to mitral replacement. However, indication and surgical technique largely depend upon the individual experience of the surgeon. The postoperative function of the reconstructed valve can be reliably assessed during the operation by left ventricular infusion of cold cardioplegic solution.