Acute bacterial endocarditis (ABE) is clinically distinct from subacute bacterial endocarditis in terms of pathologic virulence, acuteness and severity of illness, complications, and prognosis. The term infectious endocarditis may be useful as a general term but conveys no meaningful clinical information. ABE presents as an acute, fulminant intracardiac infection with fevers (temperature > 102 degrees F) that are caused by highly virulent known pathogens. Septic embolic phenomena, valve dysfunction, and congestive heart failure are characteristic. Parenteral and oral antibiotic treatment regimens are discussed.