A 42 year old woman presented with impaired filling of the right atrium and right ventricle two years after removal of uterine leiomyomas. At the time of hysterectomy, intravenous leiomyomatosis was noted, with extension of the tumor into the inferior vena cava. The tumor subsequently extended into the right atrium and coronary sinus, and protruded through the tricuspid orifice. It was successfully removed from the heart, and proved to be histologically benign.