In relation with 128 cases of surgical operation for mitral incompetence through ruptured chordae tendinae, the aetiological, anatomical and clinical characteristics of these cases were described. Bacterial endocarditis and spontaneous rupture were present in 77 percent of cases. In 94.4 percent of the cases, the patient coming to operation was in a high functional class (class III and IV of the NYHA). Operation included valve replacement in 100 cases (by a Starr-Edwards prosthesis), while the mitral valve was preserved in 28 patients. The conservative operation presently performed combined the resection-suture of the deinserted area and a reconstitutive valvuloplasty over a Carpentier's ring. Results of this surgery are good in more than 90 percent of the cases.