Isolated mycotic common iliac artery aneurysms are rare, and as such, there is no consensus opinion on management. Traditional surgical options include resection with extra-anatomic bypass, placement of allograft or antibiotic treated synthetic graft, or autogenous vein reconstruction. We report the case of a 46-year-old, human immunodeficiency virus-positive male who presented with a recurrent pneumonia and new onset of right lower quadrant abdominal pain associated with right lower extremity swelling. computed tomographic scan revealed an isolated 9.5 cm right common iliac artery aneurysm with no evidence of rupture. Preoperative blood cultures grew out Streptococcus pneumoniae. Operative repair included aneurysm resection and reconstruction using an autogenous femoropopliteal vein interposition graft from the ipsilateral thigh. The patient had an uneventful recovery with resolution of his lower extremity swelling and a normal duplex exam at follow-up. Large mycotic common iliac artery aneurysms can be successfully treated with aneurysm resection and reconstruction using an autogenous femoropopliteal vein conduit. This technique obviates the need for extra-anatomic bypass or other forms of reconstruction using prosthetic material.