Hydatid disease is a parasitic infection caused by larvae of Echinococcus granulosus, which is still endemic in many cattle-raising areas. Cardiac involvement is a rare, but potentially a very serious complication of the hydatid disease. The diagnosis of cardiac cyst hydatid may be difficult due to the nonspecific symptoms and varying clinical presentations. With this report, we describe a case of giant hydatic cyst of the interventricular septum that caused ischemic changes on ECG, mimicking acute myocardial infarction. The final diagnosis was made by combining echocardiography, MRI, and serological tests. Surgical resection of the cyst, followed by albendezol treatment yielded a favorable outcome. J Cardiovasc Med 10:425-427 (C) 2009 Italian Federation of Cardiology.