A 36-year-old man was admitted to our hospital due to infectious endocarditis and severe mitral regurgitation caused by a prolapsed anterior leaflet. Mitral valve repair with chordal replacement using expanded polytetrafluoroethylene was performed and the post operative course was uneventful. One year after the first operation, he was readmitted with a high fever and lumbargo. Echocardiography revealed vegetation on the anterior mitral leaflet and computed tomography of the brain showed cerebral infarction. Blood culture was positive for Staphylococcus aureus. Inflammatory symptoms improved following multiple antibiotic medication and the blood culture became negative. Echocardiography demonstrated the disappearance of the vegetation, but moderate grade mitral regurgitation remained. We performed mitral valve replacement instead of repair because the infectious lesion extensively destroyed the anterior mitral leaflet. In order to determine the appropriate time for surgical treatment of infectious endocarditis, we must consider several factors, such as the effectiveness of antibiotic treatment, potential cerebral complications, and the degree of damage to the valve and surrounding structures.