BACKGROUND The basic principle of non-surgical fracture treatment is to restore the original anatomical position of fractured fragments by different techniques, without direct access to the bone and without further traumatizing of tissues. Intramedullary nailing is synthesis and consolidation of fracture fragments with the main goal to gain strength and permanent placement of the implants. Two techniques of intramedullary osteosynthesis are used: with dynamic or with static intramedullary nail. Dynamization include conversion of static nail by removing screws from the longest fragment. OBJECTIVE The aim of this study is to determine whether there is a difference in the speed and quality of healing of the type A and B fractures of the femur and tibia treated by static or dynamic intramedullary nails and to compare the results. METHODS The study was conducted at the Clinic for Orthopaedics and Traumatology, Clinical Center University Sarajevo from January 2004 to June 2009. The study was retrospective-prospective, manipulative, controlled and it was conducted on a total of 129 patients with closed fractures of the diaphysis of the femur and tibia type A and type B, with different segments of bone, regardless of sex and age structure, with the exception of children under 14 years of age. RESULTS Precisely there were 47 patients with femoral fractures and 82 patients with tibial fractures. The average number of weeks of healing femoral and tibial fractures was slightly in advantage of static intramedullary osteosynthesis, it was 17.08 weeks (SD=3.382). The average number of weeks of healing in 23 patients with fractures of the femur, treated by dynamic intramedullary osteosynthesis was 17.83 (SD=2.978). We can conclude that static intramedullary nailing osteosynthesis unable movements between fragments which directly stimulates bone formation and formation of minimal callus. CONCLUSIONS Static intramedullary osteosynthesis resolve the problem of stabilizing the fracture, limb shortening and rotation of fragments.