Situations which can be considered at risk for infective endocarditis are those causing a bacteremia, which is necessary for the development of an endocarditis. Such situations can be identified by clinical studies evaluating the rate at which a bacteremia occurs after some procedures or because of lesions, then the risk of endocarditis after such a bacteremia. Without considering preexisting cardiac lesion and age, some situations seem to be at risk of subsequent endocarditis: acute bacterial infection for which antibiotherapy is necessary; procedures involving the mouth with the exception of superficial caries and bloodless supragingival prosthetic preparations; oesophageal dilatation, laser endo-oesophageal procedures, sclerosis of oesophageal varices; colonoscopy and sigmoidoscopy for cancer lesions, gastrointestinal procedures on a potentially infected gastrointestinal tract (cholecystectomy, colectomy...); tonsillectomy and adenoidectomy; naso-tracheal intubation; instrumental procedures involving the ureter or kidney, and prostatic or urinary tract biopsies and surgery; procedures performed on infected skin. In cardiac patients at high risk, in addition to the above retrograde cholangiography, colonoscopy and rectosigmoidoscopy, lithotripsy. In these situations the risk of endocarditis is probably linked to the rate of bacteremia, the size of inoculum, and the bacteria, compared with spontaneous bacteremia without any procedure, where the inoculum is low and bacteria is considered as non pathogenic. A prophylaxis has to be discussed in such situations, which are probably involved in less than 10% of endocarditis.