The authors report a case of hydatid cyst of the ventricular septum. The patient, an asymptomatic 30-year-old woman, was hospitalized in the Department of Pneumology after a routine chest X-ray test which detected two round masses in the lungs. During hospitalization the patient was asymptomatic and standard ECG was normal, but two-dimensional echocardiography (2D echo) revealed a cardiac cyst localized in the mediobasal portion of the ventricular septum. The finding was confirmed by computed tomography and nuclear magnetic resonance imaging. An echinococcosis was suspected on the basis of the patient's origin (Morocco) and because of the presence of cystic lesion also in the lungs, and was confirmed by positive hemagglutinin test. The patient underwent surgery (suction of cardiac cyst in extracorporeal circulation and washing with formaline 2%). This case is of particular interest because of the rarity of cardiac localization of echinococcosis (0.02-2%) and the lack of symptoms or of asymptomatic cardiac arrhythmias despite the location in the ventricular septum. Patients with hepatic or pulmonary hydatid disease could be routinely investigated by 2D echo because this imaging technique is: noninvasive, feasible and has a high sensitivity for detecting intracardiac echinococcal cysts.