INTRODUCTION Aorto-duodenal fistulas are rare complications of aortal prostheses. We report a case revealed by septic embolism. OBSERVATION A 63 year-old man with past history of obliterating arteriopathy of the legs and bifemoral aortal bypass was hospitalized in a dermatology unit because of bilateral ecchymotic and purpural lesions of the soles of the feet and fever. Hemocultures were positive for E. coli and alpha hemolytic streptococci. The search for a deep infectious area was negative. Gastro-esophageal fibroscopy revealed an aorto-duodenal fistula showing a fresh blood clot in the second duodenum. DISCUSSION Aorto-duodenal fistulas are rare complications of aortal prostheses, the high mortality of which is often related to late diagnosis. The initial symptoms such as fever, abdominal pain, palpable mass and digestive bleeding are inconstant and the clinical profile polymorphous. Any suspicion of septic embolism in a patient with an aortal vascular prosthesis must lead to the search for prosthetic infection and an aorto-duodenal fistula, notably in the presence of osteomyelitis at distance from the prosthesis. A scan and/or scintigraphy with normal polynuclears do not eliminate the diagnosis of an aortal-duodenal fistula and a gastro-esophageal fibroscopy should be performed.