A case of primary haemangio‐endotheliosarcoma of the right atrium is reported. A review of the literature is given and in all but four of the 56 cases, the tumour originates in the right atrium projecting into the cavity. This explains why these tumours present a rather uniform clinical picture characterized by superior vena caval syndrome combined with pericardial effusion, cardiomegaly, dyspnoea and chest pain. A male dominent sex distribution of 3 to 1 is found. The tumour is highly malignant and has caused death within an average of six months. We emphasize the possibility of early diagnosis particularly since the clinical symptoms are rather typical and cases are reported where therapy apparently was successfu