We describe the case of a patient 4 months old transferred to our hospital for evaluation of occasionally detected cardiac alterations: ecg showed abnormal Q and negative T waves in D1 - aVL leads and chest x-ray was consistent with enlargement of the left ventricular cavity. After admission, 2D echocardiographic examination disclosed, in the left ventricular cavity, a large mass extending from the papillary muscles to the outflow tract. The mass was of uniform density and easily recognizable as a tumor. Although asymptomatic, the patient underwent operation 10 months later because of the risk of occurrence of severe conduction disturbances or arrhythmias. Histological examination demonstrated that the mass was a fibroma. At post-op echocardiographic and angiographic evaluation the left ventricle appeared abnormally dilated with a large aneurysm of the lateral wall and very poor pump function. Nevertheless the patient did well in the following months until a ventricular fibrillation occurred at home. He was immediately brought to hospital and resuscitation was attempted unsuccessfully. We discuss the role of 2D echocardiography in the diagnosis of cardiac tumors, the indication of the early surgical removal and the possible limitations of the technique we used in this case.