American Heart Association published in 1997 new version of recommendations for prevention of bacterial endocarditis in risk patients. Postoperative stadium in patients with prosthetic valve belongs to the highest risk. Infection can develop during bacteremia, which occurs most frequently at stomatologic and urologic interventions. The whole scale of medical interventions can be covered by two universal antibiotical regimes--one for the mouth, respiratory and upper GI tract, second for urogenital and lower GI tract. In the first case 2 g of Amoxicillin are administered p.o. 2 hours before the intervention. Interventions are individually listed, and cases where antibiotical prophylaxis is not recommended are separately given. Special situations are discussed.