In 1955, the first AHA document on this subject was published in Circulation.6 Table 1 shows a summary of the documents published from 1955 to 1997.1,6 13 The 1960 document called atten- tion to the possible emergence of penicillin-resistant oral microflora as a result of prolonged therapy for prevention of IE, and pediatric patients were included for the first time.8 Chloramphenicol was recommended for patients who were allergic to penicillin. In 1965, the Committee published for the first time a document devoted solely to the prophylaxis of IE and recognized the importance of enterococci after GI or GU tract procedures.9 The revised recommendations published in 1972 were endorsed for the first time by the American Dental Association (ADA) and emphasized the importance of maintenance of good oral hygiene.10 This version introduced a recommendation for ampicillin in patients undergoing a GI or GU tract proce- dure. The 1977 revisions categorized both patients and procedures into high- and low-risk groups.11 This resulted in complex tables with many footnotes. The 1984 recom- mendations attempted to simplify prophylactic regimens by providing clear lists of procedures for which prophy- laxis was and was not recommended and reduced postpro- cedure prophylaxis for dental, GI, and GU tract procedures to only 1 oral or parenteral dose.12 In 1990, a more complete list of cardiac conditions and dental or surgical procedures for which prophylaxis was and was not recom- mended was provided.13 These previous recommendations rec- ognized the potential medical-legal risks associated with IE prophylaxis and suggested that the recommendations were Wilson et al Prevention of Infective Endocarditis 1737 intended to serve as a guideline, not as established standard of care. 