The purpose of this study was to investigate the effect of ozone therapy in rat femoral fractures. Following the right open femoral fractures and intramedullary Kirschner wire fixation of the fracture in 60 male Wistar albino rats, the animals were divided into two groups of 30 animals each: ozone therapy group (n=30); non-treatment (control) group (n=30). Ozone was administered by rectal insufflation. After the rats were sacrified fracture healing was assessed by biomechanical and histopathologic evaluation. Histological and mechanical findings indicated that the ozone therapy had a significantly positive effect on bone healing.