BACKGROUND: The aim of this study was to compare the clinical outcomes of native valve infective endocarditis(IE) between the mitral and aortic valvular diseases over the past 5 years in a single tertiary center. METHODS: We conducted a retrospective analysis of data in patients with IE registry at our center from 2000 to 2004. Demographics, clinical characteristics, and outcome were reviewed in the subgroup of patients with first-episode native valve IE met by definite modified Duke's criteria. Possible diagnosis, recurred cases, patients with congenital heart disease or prosthetic valves were excluded. RESULTS: A total of 36 patients were enrolled. Mean follow-up was 20.1 months. Mean age was 53.3짹14.9 years with 17(47.2%) females. Surgery was performed in 25(69.4%) of patients. Overall 1-year and 5-year survival rates were 80.3% and 57.3%, respectively. Underlying conditions according to valvular types were 13 mitral(MV group) with MV prolapse being the most(n=8, 61.5%), 18 aortic(AV group) with all having aortic regurgitation, and 5 combined MV and AV(MV+AV) diseases. Age, sex, hospitalization days, follow up days, co-morbid conditions, incidence of echocardiographic vegetation and surgery, species of blood-cultured bacteria, and in-hospital event rates were not different between the 3 groups. Intracranial complication rates and cardiac mortality were not different between the valve types. CONCLUSIONS: This retrospective study over the past 5 years in the modified Duke's criteria era showed that the clinical outcomes of native valve IE were not different between mitral and aortic valves despite of high incidence of surgery and in-hospital events.