A new case of late arterial aneurysm proximal to a corrected post-traumatic arterio-venous fistula is compared to 15 similar observations published in the last 20 years. The meantime between the vascular injury and the disclosure of the fistula was 20 years. The arteriomegaly was discovered only after the fistula was closed in 11 of the 16 cases including our case. These arterial dilatation extended primarily or secondarily from the aorta to the fistula area. Late arteriomegaly is a second reason for operating the arterio-venous fistulas. If the fistula is longstanding, the caliber of the proximal artery must be checked during and after the operation. Risks of embolism and rupture being important, all arterial dilatations must be managed by vascular replacement procedures. If the iliac artery seems uninvolved, the patient must be warned that dilatation may occur in the arterial segment proximal to the upper anastomosis. A long term survey is always mandatory.