This case of aorto-duodenal fistula was due to fistulization of a tuberculous lymph node between an atheromatous aneurysm of the infra-renal aorta and the third part of the duodenum. CAT scan provided the diagnosis of an aorto-duodenal fistula. The tuberculous origin of the fistula was confirmed by bacteriological and histological examinations. The outcome was favourable after revascularisation "in situ" combined with epiplooplasty and prolonged antituberculous drug therapy.