Impaction bone grafting shows encouraging early results as a method of immediately restoring leg length, while allowing weight-bearing as tolerated, in the treatment of large segmental femoral defects after femoral shaft and metaphyseal non-unions. The operative technique followed is described in three consecutive cases and the effectiveness of impaction bone grafting for femoral non-unions with associated large segmental bone defects has been demonstrated. Between 80 and 120 cm3 of coarsely milled irradiated bone allograft was used to reconstruct the defects, which were contained in malleable metal mesh. All three patients were fully weight-bearing by three months postoperatively. At two years follow-up, plain radiographs demonstrated maintenance of reduction and healing in all three cases.