The purpose of this study is to determine the clinical features with the best preoperative diagnostic value for aortocaval fistulas (ACF) associated with abdominal aortic aneurysm (AAA). A review of our experience of seven patients presenting ACF between 1980 and 1994 as well as an extensive study of the literature provide a clearer picture of the signs and symptoms allowing diagnosis of ACF: edema of the lower extremities and signs of venous hypertension are the most predictive findings; continuous abdominal murmur is noted in 66% of cases and is of good diagnostic value.