A 67 year-old asymptomatic patient was referred to our echo-lab because of hypertension. Transthoracic 2D-echocardiogram showed a non-prolapsing ovoid mass attached to the left side of the interatrial septum. Transesophageal echocardiography evidenced an ovoid cavitated mass with internal areas of calcification. Color Doppler revealed flow inside the cavities. At surgery, a multicavitated mass was observed attached to interatrial septum. Macroscopically revealed cavities filled with blood, as well as partially calcified areas. Microscopically there were collections of "lipidic" cells embedded in the myxoid matrix, typical of cardiac myxoma. Cardiac hydatid cysts usually have a rounded shape. Most myxomas are solid masses without a cystic architecture or cavitations. Calcification is usually identified at a microscopic level. The combination of a polycystic appearance of the mass and macroscopic areas of calcification is more frequently observed in hydatid cysts than in cardiac myxomas. This appearance of the mass leads us to consider a cardiac echinococcal cyst as the first diagnostic possibility. This peculiar structure of cardiac myxoma, to the best of our knowledge, has never been documented. Transthoracic echocardiography and particularly transesophageal imaging, enable us to delineate this kind of tumors. Surgical resection is the appropriate treatment for these tumors, even in asymptomatic patients.