Cardiac involvement in Morquio syndrome, mucopolysaccharidosis IV, is characterized by aortic and mitral valve thickening and infiltration of the coronary arteries. There are few reports concerning surgical interventions in patients with mucopolysaccharidoses. We report a case of a patient affected by Morquio syndrome who underwent aortic valve replacement surgery for severe aortic valve stenosis, with an uneventful postoperative course. Cardiac surgery appears safe and feasible in these patients and improves the quality of life, even if the future prognosis related to the underlying disorder should be considered.