Thus, on the basis of the weight of clinical evidence involving nearly 2000 patients in the current literature, it appears that patients suspected of having IE should be clini- cally evaluated, with the modified Duke criteria as the primary diagnostic schema. It should be pointed out that the Duke cri- teria were originally developed to facilitate epidemiological and clinical research efforts so that investigators could com- pare and contrast the clinical features and outcomes of various case series of patients. Extending these criteria to the clinical practice setting has been somewhat more difficult. It should also be emphasized that full application of the Duke criteria requires detailed clinical, microbiological, radiological, and echocardiographic queries. Because IE is a heterogeneous disease with highly variable clinical presentations, the use of these criteria alone will never suffice. Criteria changes that add sensitivity often do so at the expense of specificity and vice versa. The Duke criteria are meant to be a guide for diag- nosing IE and must not replace clinical judgment. Clinicians may appropriately and wisely decide whether or not to treat an individual patient, regardless of whether the patient meets or fails to meet the criteria for definite or possible IE by the Duke criteria. We believe, however, that the modifications of the Duke criteria (Tables 2 and 3) will help investigators who wish to examine the clinical and epidemiological features of IE and will serve as a guide for clinicians struggling with dif- ficult diagnostic problems. These modifications require fur- ther validation among patients who are hospitalized in both community-based and tertiary care hospitals, with particular attention to longer-term follow-up of patients rejected as hav- ing IE because they did not meet the minimal floor criteria for possible IE. 