Despite a lack of certain knowledge regarding the role of the teeth in the aetiology of endocarditis, antibiotic prophylaxis should be given before gingival blood vessels are opened in cases of rheumatic heart disease. Much higher doses are required in patients with prosthetic heart valves. Full clearance of the teeth should be considered when a patient has already had an attack of endocarditis or where a prosthetic heart valve has been placed. Strict oral health is required in patients at risk.