Aortocaval fistula is an uncommon complication of ruptured abdominal aortic aneurysm and is only seen in 4% of all ruptured aneurysms. The symptoms may vary from one patient to another but the characteristic physical findings are high output heart failure, widened pulse pressure with low diastolic blood pressure and venous hypertension. When these signs are combined with an abdominal aortic aneurysm and a continuous abdominal bruit, the diagnosis of aortocaval fistula must be seriously considered. It is important to diagnose the fistula before surgical intervention, so as to prevent intraoperative bleeding and complications. In our surgical department we have operated 103 ruptured abdominal aortic aneurysms but only one with an aortocaval fistula. This case is discussed in the light of the literature on the subject.