Submitral left ventricular aneurysm is a rare cardiac pathology. Etiology remains still mysterious, but it is believed to be due to a congenital defect of the fibrous layer of the atrioventricular junction. Surgical closure of aneurysm rim is the therapy of choice, despite the diversity of surgical approaches and techniques. We present a young patient operated with a transmitral approach in our clinic. Posterior mitral leaflet (PML) detachment and then extension valvuloplasty by using autologous pericardium was performed in order to save the native mitral valve. We believe that respecting the integrity of native valve is of crucial importance in this young population of patients.