The authors report the case of a pediculated left atrial ball thrombus whose embolisation and ejection through the aortic valve was recorded during transesophageal echocardiography. The value and risks of transesophageal echocardiography for the diagnosis of left atrial masses are reviewed in the light of this case and a review of the literature. The prognosis and therapeutic implications of a left atrial ball thrombus are also described.