Conventional valves have a sewing ring that reduces the effective orifice area for a given valve size. In patients with small aortic roots, the implantation of a stented conventional prosthesis can be very difficult or may lead to patient-prosthesis mismatch. In the case of the Sorin Perceval sutureless aortic valve, concomitant mitral valve replacement (MVR) is an exclusion criterion because the latter valve's rigid ring may interfere with the self-expandable stent anchorage of the Sorin Perceval sutureless valve, or cause it to become distorted. The case is reported of very small, 77-year-old woman with severe aortic valve stenosis, severe mitral regurgitation and asymmetric hypertrophy of the left ventricle with systolic anterior motion. The patient underwent MVR and concomitant off-label implantation of the Sorin Perceval S sutureless valve due to the extremely small size of the aortic annulus. Echocardiography performed on completion of surgery, at discharge from hospital and at after a four-month follow up, documented a normal mitral prosthesis position and function, a normal aortic prosthesis position, and mild central regurgitation in both valves.