Nine patients with anatomically documented vegetations on one or more cusps of the aortic valve had echocardiograms in which abnormal echoes were associated with the aortic leaflet echoes. The motion of the abnormal echoes during systole correlated well with the anatomic location of vegetations: a vegetation on the right coronary cusp moved anteriorly with systole while a vegetation on the noncoronary cusp moved posteriorly during systole. Our data, although inconclusive, suggest that echoes from a vegetation on the left coronary cusp maintain a mid-aortic position throughout the cardiac cycle. The echocardiographic appearance of vegetations is not specific, but in the setting of septicemia, dense mobile echoes in the region of the aortic valve are strongly suggestive of vegetation. A normal echocardiographic appearance of the aortic valve does not exclude the possibility that vegetation is present, especially if the growth is less than 5 mm in size.