During probation of the authors at the Dept of Thoracic and Cardiovascular disease, La Pitie - Salpetriere hospital, Paris, I had the opportunity to follow up and participate in the operation of' a case with tumor of right atrium. The tumor occurred in a previo.usly healthy, young patient who liked to play sports. Six months ago, the patient was treated in another hospital (Moulhouse I. hospital) with the diagnosis of bacterial pericarditis. On admission to the Dept of Thoracic and cardiovascular disease La Pitie Salpetriere hospital, it was diagnose as tumor of the right atrium. The whole tumor was removed and the defect in the right atrium was repaired by a Vascutex graft. The patient made a good recovery after the operation. Histologie study showed an angiosarcoma. According to Prof. L. Gandjbakhch, chief of the Department, this tumor is so rare that during the last 20 years he saw only 5 cases.