Eight cases of left ventricular rupture at the atrio-ventricular groove among 693 mitral valve replacements, isolated or associated with other surgical procedures, are reported. In the authors' opinion, the surgical technique of the mitral valve's removal, especially if calcific or with subvalvular disease, as well as the method and the site of implantation of the prosthesis, are the main factors in determining this severe complication. In order to avoid the rupture of the posterior wall of the left ventricle, a simple modification of the surgical technique which reinforces the valvular annulus is suggested.