The recommendations for endocarditis prophylaxis from the American Heart Association have changed for three main reasons: 1) most cases of endocarditis are not attributable to an invasive procedure but rather are the result of randomly occurring bacteremia from routine daily activities; 2) prophylaxis may only prevent a small number of cases of infective endocarditis in women undergoing genitourinary procedures; and 3) the risk of antibiotic associated adverse events exceeds the benefit, if any, from prophylactic antibiotic therapy. The specific changes pertinent to the obstetrician-gynecologist are discussed.