A left lower quadrant bruit, reduced left dorsalis pedis pulse, and left leg edema were found in an elderly male presenting with chest pain, hypotension, heart failure, and azotemia. Measurement of cardiac output, 12.3 1/minute, systemic vascular resistance, 349 (normal, 770-1500), and arterial-mixed venous oxygen differential, 1.3 (normal, 10-20) confirmed the suspicion of AV fistula, which was shown by arteriogram to be left common iliac artery to iliac vein. Repair was accomplished without incident and the patient made an excellent recovery. This patient's AV fistula is an excellent example of a treatable cause of high output congestive heart failure. Further, his rapid recovery after fistula repair undertaken in the setting of hypotension, renal failure, and refractory heart failure emphasizes the need for aggressive surgical intervention.