Heterotopic liver tissue has been described in the literature, more commonly observed in the abdominal cavity than in the thoracic cavity. In most reported supradiaphragmatic ectopic liver cases, there was a pedicle passing through the diaphragm and connecting the liver with the ectopic tissue. We report a case of heterotopic liver tissue misdiagnosed preoperatively as atrial myxoma. A 40 yearold woman presented to the Emergency Department with recurrent acute nocturnal respiratory distress. Transthoracic echocardiogram revealed a 2 x 2.5 cm floating mass in right atrium at the junction of inferior vena cava. The patient underwent sternotomy for resection of the atrial mass based on presumed diagnosis of cardiac myxoma. Pathologic examination demonstrated polypoid encapsulated benign hepatic tissue. We presented this case because it is an extremely rare condition that is commonly misdiagnosed, and is the second case to date, to the best of our knowledge, of supradiaphragmatic heterotopic liver polyp identified inside the cardiac chambers in a living adult person.