Infective endocarditis is a rare, serious, and sometimes fat heart disease that can be caused by bacteremia from the mouth, especially by Streptococcus viridans. As a result, dental procedures have often been blamed for cases of infective endocarditis, but poor oral health and hygiene may actually cause more cases of infective endocarditis than d o dental procedures. The American Heart Association and other groups have published recommendations for the prevention of infective endocarditis in dental patients and advise specific antibiotic regimens for certain dental procedures in cardiac-abnormal patients. The most recent (1990) American Heart Association recommendations are the most conservative yet, reflecting concern about the prevention of not only infective endocarditis, but also problems resulting from the antibiotics themselves. Clinicians should carefully consider not only the patient's medical history, but also the types of dental procedures planned.