Frequently, the presence of endocarditis is disguised. The emphasis of this description of the clinical manifestations of endocarditis is on the various modes of presentation, rather than on individual symptoms and signs. Endocarditis can manifest with cardiac, pulmonary, ophthalmic, central nervous system, renal, orthopedic, phthisic, and peripheral vascular disorders. The following clinical data are most useful in helping to establish a diagnosis of endocarditis: a history of fever, anorexia, weight loss, and back pain; a search for petechiae; splenomegaly; and daily examination, especially cardiac auscultation and funduscopic examination, of those patients in whom incomplete evidence exists at admission. The most helpful laboratory tests include those revealing anemia, increased erythrocyte sedimentation rate, abnormalities in the urine compatible with nephritis, or embolization. In patients who have not received antimicrobial therapy just before the diagnostic workup, one set of three blood cultures is sufficient to isolate the offending microorganism in about 95% of cases.