PURPOSE: The purpose of this study is to present our experience with open reduction, 3.5-mm reconstruction plate fixation, bone-grafting, and postoperative early mobilization for nonunions of midshaft clavicular fractures. MATERIALS AND METHODS: Sixteen patients were treated operatively for nonunions of the midshaft of the clavicle from 1997 to 2001. Ten nonunions were atrophic and six were hypertrophic. Nonunion had been present for an average of 6.5 months. The operative technique included removing the fibrous tissue from the nonunion site and opening the medullary canal, reduction of the fracture and fixation with a 3.5-mm reconstruction plate, and bone-grafting. Postoperative mobilization started within one week. RESULTS: The average duration of follow-up was 22.0 months. All fractures were united in an average of 10.0 weeks. All patients had full range of motion of the ipsilateral shoulder, but 3 out of 6 patients who were more than 50 years old complained occasional pain in the ipsilateral shoulder at the final follow-up examination. There were no major complications of postoperative infection, metal failure of the plate, loss of fixation, nonunion, and refracture after removal of the implant. CONCLUSION: The technique of open reduction, reconstruction plate fixation, and bone-grafting is a safe and reliable method to allow early rehabilitation by stable fixation and to predict a high rate of union for nonunions of midshaft clavicular fractures.