Background: Reamed interlocking intramedullary nailing is considered the gold standard treatment for complex fractures of the femoral and tibial shaft. There has been some controversies about dynamization of statically locked nails, and some authors recommended routine dynamization for promotion of healing. This study aims to evaluate treatment of complex fractures in tibia and femur with static interlocking intramedullary nail method.Methods: In a retrospective study from January 2003 to April 2008, 173 patients with femoral and tibial shaft fracture that were treated with this method were enrolled. No rod was dynamized in our patients.Results: All patients with tibial fractures achieved union without any need for dynamization during 12-18 weeks (mean; 13.4 weeks). Four patients developed delayed union but all achieved union without any intervention. In femoral fracture, all but one patient achieved complete union during 10-30 weeks (mean: 18.3 weeks). One patient developed non-union who was treated by an exchange nailing and iliac bone graft method. No significant complication was observed in our patients.Conclusion: It is not necessary to routinely dynamize nails in tibial and femoral shaft fractures as all fractures united in acceptable alignment without any complication.