To improve the diagnosis and treatment of infective endocarditis (IE) by exploring its causes, pathogenic microorganism and clinical characteristics. The clinical data of 120 IE patients treated in Peking Union Medical College Hospital from October 1997 to September 2007 were analyzed retrospectively. Of the 120 consecutive cases diagnosed as IE according to the Duke's new criteria, 79 were male and 41 female with a average age of (43.2 +/- 16.7) years old. Twelve cases were prosthetic valve endocarditis (PVE) and 108 cases native valve endocarditis (NVE) and there were no previously known heart diseases in 29 of the cases. Seventy-nine of the 108 (73.1%) NVE patients had basic cardiac abnormalities before IE diagnosis, such as congenital cardiovascular disease (30 cases), idiopathic mitral valve prolapse (23 cases) and rheumatic heart disease (11 cases). Fever (100.0%), anemia (54.2%) and embolism (48.3%) were the most common clinical manifestations in the IE development. Of the 83 patients who had a positiv