Résumé : A 58-year-old woman has dyspnea and palpitations which reveal a leiomyosarcoma of the right ventricle. The medical imaging shows a lobulated sessile tumor attached to the ventricular septum and the tricuspid valve extending into the pulmonary artery trunk. The resection is performed with a tricuspid valvoplasty. In spite of chemotherapy (epirubicin-cyclophosphamide), relapse is observed with pulmonary metastases 17 months after the surgery. The death becomes on 18 months in congestive heart failure. From this case, the authors make a review of the literature about this exceptional tumour, and talk over the low possibilities of treatment, despite the capacities of the new ways of diagnosis.