Although transcatheter aortic valve implantation (TAVI) has been performed successfully in patients with aortic stenosis and a mechanical mitral valve, to the present authors' knowledge only one report has been made of this being achieved in a patient with a ball-cage-type mechanical mitral valve. In the present case, as the cage section of the mechanical valve was inclined towards the left ventricular outflow tract (LVOT), there was a risk of interaction between the prosthesis and mechanical valve during the TAVI procedure. The successful implementation is described of a self-expandable aortic prosthesis in a patient with a ball-cage-type mechanical valve inclined towards the LVOT.