Malignant primary cardio-pericardial tumours are rare and difficult to diagnose because of the diversity of their clinical expression. The authors report a case of pericardial angiosarcoma and review the literature, underlining the value of new non-invasive imaging techniques in the diagnosis and surgical approach to obtaining histological confirmation. Magnetic resonance imaging is a valuable tool in this context as it allows scanning of the tumoral extension in all spatial planes and the visualisation of the haemorrhagic signs of malignancy the pericardial effusion related to this pathology.