An infant with neonatal Marfan syndrome (nMFS), a condition that is nearly always lethal during infancy, was referred to our hospital with symptoms of congestive heart failure resulting from severe mitral valve insufficiency. During mitral valve repair, the use of an annuloplasty ring was waived until annular dilatation was achieved after 2 palliative mitral valvuloplasty procedures. After the definitive operation, the patient’s mitral valve function remained within normal limits until the last follow-up when the patient was 11 years old. To the best of our knowledge, this patient has the longest recorded survival after mitral valve repair.