The echocardiograms of 17 patients with proved infective endocarditis were surveyed to assess the reliability of echocardiography in this disease. Vegetations were present on 20 valves (11 aortic, 7 mitral, 2 tricuspid) at surgery or autopsy. Echocardiography correctly identified the abnormality in 11 valves. There were 8 valves with false-negative studies of which only one examination was technically inadequate. One false-positive echocardiogram was found. A negative echocardiogram does not exclude infective endocarditis. The size of the vegetation is not the only consideration in its detection echocardiographically. False-positive and false-negative studies are discussed.