Traumatic arteriovenous fistula (AVF) is not an uncommon disorder, but late discovery and the presentation of high-output heart failure is very rare. This patient did not know that he had traumatic AVF after a gunshot injury in the left thigh 14 years ago. The major presentation of the AVF was signs of heart failure. We performed surgical repair after making the diagnosis. The patient recovered with an uneventful course. This report stresses the importance of history-taking and physical examination in making the diagnosis of traumatic AVF.