A rare case of abdominal aortic aneurysm associated with crossed-fused ectopic kidney in a 74-year-old man is reported. On enhanced CT scans, the maximum diameter of his infrarenal aortic aneurysm was 55mm, and he lacked a right kidney. A crossed ectopic kidney was fused to the lower part of the left kidney. On preoperative examinations, only one feeding artery to the ectopic kidney separated from the right common iliac artery. However, laparotomy confirmed the presence of three aberrant renal arteries, the middle one of which was very slim. Aneurysmectomy and a bifurcated artificial graft replacement was performed. After proximal anastomosis, the two larger aberrant renal arteries were reconstructed under renal protection with intermittent infusion of cold Ringer's solution. The smallest aberrant renal artery was ligated. Postoperatively, this patient recovered without any complications. In operations for abdominal aortic aneurysm associated with renal anomaly including ectopic kidney, horseshoe kidney, and pelvic kidney, it is important to elucidate the anatomy of aberrant renal arteries preoperatively, and reconstruct as many of these arteries as possible. This report is apparently the fourth on abdominal aortic aneurysm associated with crossed ectopic kidney.