The role of vegetation as the key feature of infective endocarditis is universally recognized. Nowadays, the wide availability of transesophageal echocardiography has made of it the most employed technique to establish the diagnosis by visualizing vegetations. However, the factors which influence the size of vegetation when first detected are not clearly determined. Furthermore, there is considerable controversy regarding the prognostic implications of the size of vegetation. This is of paramount significance to early identify patients at high risk for complications, which might benefit from aggressive attitudes. We present a study based on TEE. Our results show that the size of vegetation at admission is mostly determined by anatomical and not microbiological factors, and the prognostic influence of vegetations on the risk of embolisms, need of surgery, persistent infection and septic shock.