Résumé : Purpose: To determine the relative rates of common iliac artery (CIA) expansion after elective straight aortic tube-graft replacement of infrarenal abdominal aortic aneurysms (AAA). Methods: Five participating centers in this 2004 study entered patients they had managed by an aortoaortic tube graft for elective AAA repair. The procedures took place between January 1995 and December 2003. Postoperative computed tomography (CT) scans were obtained for all patients in 2004 to assess changes in CIA diameter. Measurements on preoperative and postoperative CT scans were all made at the same level using the same technique. Results: Entered in the study were 147 patients (138 men, 9 women) with a mean age of 68 years. Mean follow-up from aortic surgery to verification of CIA diameter on the postoperative CT scan was 4.8 years. Mean preoperative CIA diameter was 13.6 mm vs 15.2 mm postoperatively. No patient developed occlusive iliac artery disease during follow-up. Three patients (2%) required repeat surgery during follow-up for a CIA aneurysm. The 147 patients were divided into three groups based on preoperative CIA diameter shown in CT scan: group A (n = 59, 40.1%), both CIA were of normal diameter; group B (n = 53, 36.1%), ectasia (diameter between 12 and 18 mm) of at least one CIA; group C (n = 35, 23.8%), an aneurysm (diameter >18 mm) of at least one CIA. CIA diameter increased by a mean of 1 mm (9.4%) over 5.5 years in group A vs 1.7 mm (12.1%) over 4.3 years in group B and 2.3 mm (12.7%) over 4.2 years in group C. The three patients who required repeat surgery for a CIA aneurysm during follow-up were all in group C. Four variables were associated with aneurysmal change in CIA: initial CIA diameter, celiac aorta diameter on the preoperative CT scan, a coexisting aneurysm site, and the follow-up duration. Conclusions: Tube-graft placement during AAA surgery is justified even for moderate CIA dilatation (<18 mm). CIA aneurysms with a preoperative diameter ≥25 mm enlarge more rapidly and warrant insertion of a bifurcated graft during the same surgical session as AAA repair. The evolutive potential of CIA between 18 mm and 25 mm in diameter justifies a bifurcated graft when the celiac aorta diameter is >25 mm or the patient's life expectancy is ≥8 years. © 2006 The Society for Vascular Surgery.