Right-sided infective endocarditis (IE) is rare in Japan, probably because rate of drug addiction is lower in Japan than in the Western countries. We diagnosed three cases of right-sided IE using transthoracic echocardiography: two were isolated tricuspid valve IE, and one was pulmonary valve IE complicated with ventricular septal defect (VSD) and double-chambered right ventricule (DCRV). Two cases of isolated tricuspid valve IE were successfully treated by cardiac surgery: In one, the treatment consisted of vegetectomy and leaflet repair; in the other, replacement of the tricuspid valve. A thrid case ended with the sudden death of the patient before surgery. Transthoracic echocardiography proved useful for clinical diagnosis and follow-up of right-sided IE, as well as for clinical selection of surgical procedures.