A 26-year-old male patient presented with complaints of pain, dyspnea, and hemoptysis of one-week history, while on oral anticoagulation treatment that had been started two years before upon the diagnosis of pulmonary thromboembolism. Transthoracic echocardiography showed two mass lesions in the right atrium and inferior vena cava, measuring 3.5x3 cm and 1.5x1 cm, respectively. The possibility of vegetation or secondary cardiac tumor was excluded by further examinations and, considering consistent oral anticoagulation, no other cause could be determined related to thrombus formation. Multiple cardiac myxomas were thought for the differential diagnosis and the patient underwent surgery. Histopathologic diagnosis of both masses was thrombus.