A 78-year-old Japanese male with previous gastric cancer and untreated diabetes mellitus was admitted to hospital for persistent fever and leg edema. Blood culture was positive for Streptococcus angino'sus, and echocardiography showed isolated tricuspid valve infective endocarditis. Infection was controlled with intravenous antibiotics, but surgery was indicated because of persistent severe regurgitation and large vegetation of 15 mm in size. As the tricuspid valve anterior leaflet was extensively damaged, he underwent valve replacement using a bioprosthetic valve. The patient was discharged 25 days postoperatively with additional antibiotics, and he has been free from recurrent endocarditis for 6 months.