To investigate the effects of closed reduction and ulna intramedullary nail fixation for the treatment of fresh Monteggia fractures of Bado type I and II in children.Twenty-three children patients with Monteggia fracture during July 2010 to September 2013 were treated by closed reduction and ulna intramedullary nail fixaion including 18 boys and 5 girls with an average age of 9.3 years old ranging from 6 to 13 years old. Among them,15 cases were Bado type I and 8 cases were Bado type II. There were 9 cases with radial nerve injury. The operation time,the recovery of nerve injury, the fracture healing and the function of elbow were observed and recorded.All patients were followed up for 6 to 24 months (12 months on average). All patients were obtained bone healing. According to Anderson standard, at the final follow-up, 20 cases got excellent result, 2 cases got good result, and one case got fair result.Treatment of the fresh Monteggia fractures in children by closed reduction and ulna intramedullary nail fixation has advantages of simple operation, less trauma and good results.