Intravenous leiomyomatosis is an uncommon clinical entity characterized by the growth of a benign, smooth muscle tumour within the venous system. Intracardiac extension of this tumour is rare, and approximately 35 cases have been reported in the literature. The second case of massive intracardiac extension of intravenous leiomyomatosis is reported in a pregnant patient diagnosed after the unusual presentation of seizure activity. Tumours were successfully removed from the right internal iliac vein, inferior vena cava, and right atrium and ventricle in a single-stage operation using cardiopulmonary bypass and circulatory arrest. Concomitant total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed. Nine months after diagnosis, the patient was evaluated for recurrent disease. A review of the literature from 1994 to 1998 is presented.