Primary aortoenteric fistulae (AEFs) are rare vascular entities. More than 75% of primary AEFs involve the duodenum, with the overwhelming majority located in the third or fourth portion. Atherosclerosis, leading to formation of an aortic aneurysm, remains the most common etiology, accounting for more than 3/4 of the cases reported. Primary aortoenteric fistulae following radiotherapy are rare. The case of a 49-year-old man with aortoduodenal fistula 22 years after para-aortic radiation is presented. In November 1997, the patient suddenly developed hematemesis and melena. Endoscopy suggested the presence of an ulcus but no definitive bleeding source could be seen. Bleeding stopped spontaneously. Six hours later he developed massive hematemesis and was transferred to our department. An emergency operation was performed. We found an aorto-duodenal fistula in the third portion of the duodenum without an aortic aneurysm. We directly sutured the aortic wall laceration and resected the third and fourth part of the duodenum. Histology revealed typical signs of radiation damage. The patient is alive and well 2 years after surgery. To our knowledge, this is the sixth case of a primary aorto-duodenal fistula following radiotherapy ever to be reported in world literature.