A 28-yr old female patient admitted to our clinic because of dyspnea and chest pain. Her transesophageal echocardiography demonstrated a huge mass on the anterolateral wall of the left ventricle causing dysfunction of the myocardium. Coronary angiography demonstrated left anterior descending artery fistula draining into the pericardial cystic mass. Hydatic cyst was suspected and ELISA and hemagglutinin tests were both negative for Echinococcus granulosus. Magnetic resonance image of the heart showed a mass thought to be a hematoma inside the cyst. She underwent surgery. The cystic lesion with a pure hematoma inside, was excised, and the fistula between left anterior descending artery and the mass was ligated without any complications. To our knowledge, this is the first case of a pericardial hematoma due to a coronary artery fistula, in the English literature. (C) 2001 The International Society for Cardiovascular Surgery. Published by Elsevier Science Ltd. All rights reserved.