Intravenous leiomyomatosis is a rare, benign neoplasm of the uterine, affecting adult women. We report two cases in whom intravenous leiomyomatosis extended through the inferior vena cava into the right heart chambers and the pulmonary artery. Both patients underwent staged operation with excision of the cardiac and primary tumour. The differential diagnosis of a right atrial mass in middle-aged women should include intravenous leiomyomatosis.