A case of misdiagnosed infected superficial femoral artery aneurysm is presented. It was initially misdiagnosed as thrombophlebitis. Surgical excision and repair with a saphenous vein interposition graft was performed. The diagnosis of this disease is difficult because there is a lack of signs and symptoms. Staphylococcus aureus and enterobacter are the two most common organisms responsible for infected peripheral aneurysms. Surgery is the standard treatment: ligation, drainage and resection with or without arterial reconstruction depending upon the aneurysm localization.