Aortocaval fistula (ACF) is a rare complication of abdominal aortic aneurysm and often remains undiagnosed until the aneurysm is opened. Major complications from repair of ACF are congestive heart failure due to fluid overload, pulmonary embolization and shock from massive hemorrhagelP. The anesthetic management includes a number of critical aspect, since a delay in the treatment may lead to potentially lethal disorders. To demonstrate that hematuria is an important sign of ACF, we present a case urgently operated on for ruptured iliac aneurysm, in which ACF had not been diagnosed before operation.