It is commonly believed that prosthetic valve implantation in actively infected patients is to be avoided. After normalization of C-reactive protein and white blood cell counts, and sterilization of blood cultures by treatment with antibiotics, we performed valvular surgery. We performed mitral valve repair in cases where the mitral valve lesion did not involve the annulus. From July 1992 to November 1996, 13 patients (mean age, 50 years) were treated surgically for infective endocarditis (IE) at Kansai Medical University. Twelve of the patients had native valve endocarditis (NVE), and 1 had prosthetic valve endocarditis (PVE). In 6 patients, the causative organisms were determined. These included: α-Streptococcus in 4 patients, Enterococcus in 1, and methicillin-resistant Staphylococcus aureus (MRSA) in 1. The affected valves were as follows: aortic valve alone in 4 patients, mitral valve alone in 6, aortic and mitral valves in 2, and a prosthetic aortic valve in 1. The PVE was due to a MRSA infection which occurred 9 months after aortic valve replacement. All patients were treated preoperatively for heart failure and the infection. The surgical procedures performed were: aortic valve replacement in 4 patients, mitral valve replacement in 3, mitral repair in 3, double valve replacement in 2, and re-aortic valve replacement in 1. There were no deaths or recurrences of IE in hospital or during follow-up to date. In all of the mitral valve repair cases, the mitral regurgitation on follow-up echocardiograms was grade I. Our results show that surgical treatment of IE after management of preoperative conditions can be successful. Furthermore, despite the absence of laboratory findings indicative of ongoing inflammation or infection, pathologic examination revealed active inflammatory reactions and organisms in 4 cases. In 1 patient, MRSA was culthued from an annular abscess that was resected intraoperatively. We suggest that cessation of antibiotic therapy be regarded with caution and suggest that the infected site must be resected surgically.