PURPOSE: The aims of this study were to determine the effectiveness of the treatment using augmentation plate fixation for nonunion of long bone fracture after interlocking intramedullary nailing MATERIALS AND METHODS: Thirteen patients with nonunion of the long bone fracture after interlocking intramedullary nailing who underwent augmentation plate fixation were evaluated; followed up for more than 1 years. We evaluated five patients with nonunion of the humerus, three of the tibia and five of the femur. Twelve of thirteen patients were carried out autogenous cancellous bone graft and augmentation plate fixation was performed without removal of intramedullary nail for all patients. RESULTS: For the cause of nonunion, seven patients were by iatrogenic factors such as insecure fixaton and six patients were by fracture itself such as severe comminution and open fracture. Bone union was achieved in thirteen patients all and the average bony union time was 4.2 months (ranged from 3 to 5.5 months) for the humerus, 6.4 months (ranged from 4 to 8.5 months) for the tibia and 7.3 months (ranged from 5.5 to 9 months) for the femur. There were no complications such as reoperation, infection or plate failure. CONCLUSION: TAugmentation plate fixation is effective treatment option for the management of long bone fracture nonunion after intramedullary nailing.