Background: Secondary aortoenteric fistula is an iatrogenic complication after aortic reconstructive surgery presenting with gastrointestinal bleeding and/or infectious symptoms. Infrequently, it may manifest with nonspecific and atypical clinical signs. We present a case of necrotizing fasciitis of the thigh complicating secondary aortoduodenal fistula, diagnosed with CT-scan. Case presentation: A 67-year-old man with a history of an open aortic-bifemoral bypass 6 years ago was admitted for a progressively swollen and painful right thigh for the last month. Through laboratory and morphological (CT-scan) investigations, a secondary aortoduodenal fistula associated with necrotizing fasciitis of the right thigh was discovered. After general supportive care and empiric antibiotherapy, the patient underwent a prosthetic explantation, a resection of the perforated bowel with end-to-end anastomosis, and extensive debridement of the necrotic tissue of the thigh. No revascularization has been attempted. The patient died the next day of multiple organ failure. Conclusion: Secondary aortoenteric fistula is rare but with a poor prognosis. Clinical presentation is not always typical. A high index of suspicion is the most important factor for improving outcomes. There is not a consensus about optimal management. Axillo-bifemoral revascularization and subsequent graft removal seem to be the best therapeutic option.