Horseshoe kidney is a common renal anomalies, but coexistence with abdominal aortic aneurysm (AAA) is rare. Horseshoe kidney may cause various technical difficulties of aneurysm repair. A 76-year-old man was referred to our hospital for treatment of AAA with a horseshoe kidney. Preoperative 3-dimensional computed tomography (3D-CT) scans showed a pair of normal renal arteries and 3 accessory renal arteries from the anterior wall to abdominal aorta just proximal to an aneurysm. At operation, the aneurysm was exposed through a transperitoneal approach, and artificial graft replacement was performed with a woven Dacron bifurcated graft preserving the renal isthmus. The accessory renal arteries were not reconstructed. The postoperative course was uneventful. Postoperative 3-D CT showed minor infarction of renal isthmus, but renal function was not impaired.