The clinical manifestations, infective microorganisms, underlying diseases, complications and prognosis of infective endocarditis (IE) were studied in 17 current patients. Data were compared with 101 previous cases reported in Japan. Most patients with IE (110/118 = 93.2%) had underlying heart diseases. IE was noted most often in patients with ventricular septal defect (VSD) and tetralogy of Fallot. The incidence of post operative endocarditis was high (29.4% in the present series and 9.0% in the overall series), too. Streptococcus viridans, Staphylococcus aureus and GNB were the most common etiologic agents with incidences of 28.8% (34/118), 25.4% (30/118) and 9.3% (11/118), respectively. Almost half of the deaths from IE were caused by s. aureus. The mortality was 11.9% (14/118) in both series. The death rate from candida albicans was 100%, from s. aureus 33.3% (10/30) and from str. viridans 5.9% (2/34) in both series. Culture negative patients accounted for 11.9% (14/118) in both series. Complications which did not involve the valves were noted in one patient with cerebral emboli and in two patients with pulmonary infarction in the present series. Cerebral emboli phenomena were seen 8 cases of the overall series, 4 of whom died.