Summary
1. two cases, one successfully treated, of aorto‐caval fistulae, due to rupture of an abdominal aneurysm are reported.
2. it is re‐emphasized that such a lesion is compatible with life and the duration of symptoms and survival is in major part dependent on the size of the communication.
3. the syndrome of pain, abdominal mass, bruit and thrill, and high caval pressure leading to collapse, venous congestion and renal failure is described.
4. it is suggested that such cases are surgical emergencies: that infusions may be dangerous and the presence of cardiac failure should not automatically eliminate the possibility of surgical care. the fistula, which may be several centimetres in length can be managed with or without caval control.