Intravenous leiomyomatosis is an uncommon benign tumor arising from either the uterine venous wall or uterine leiomyoma. Although this tumor is usually confined to the pelvic cavity, sometimes it can extend into the cardiac cavity and brings on sudden death. We report a case of intravenous leiomyomatosis extending into the right atrium, right ventricle and both pulmonary arteries by seeding. The tumor was detected with transthoracic echocardiography and appropriately diagnosed by transesophageal echocardiography and cardiac MRI. Entire tumor was successfully removed by one-stage radical surgery under cardiopulmonary bypass.