We report the results of a single centre prospective study of exchange nailing for aseptic non-union of a femoral fracture. Eighteen patients with 19 aseptic femoral non-unions had exchange nailing performed in our institution. We collected data on mechanism of injury, original fracture type, and indication for exchange nailing, further surgery and major complications. In 11 non-unions (58%), the exchange nail procedure alone resulted in fracture union with a mean time to radiographic union of 9 months (range 3-24 months). The non-union did not heal in five patients, two patients developed an infected non-union, and one patient required dynamisation of the exchange nail. Fracture healing was eventually achieved in 18 non-unions (95%). Complications following exchange nailing occurred in 11 fractures (58%), in which further surgery was required (four repeat exchange nailings, two Ilizarov frame applications and five nail removals). The role of reamed exchange nailing in the treatment of femoral non-union needs to be re-evaluated. Although fracture healing is eventually achieved in most patients, a significant number of them required additional surgery to achieve union or to deal with complications arising from the exchange nailing.