Distraction Osteogenesis (DO) is a surgical technique used to reconstruct bone defects. In the maxillofacial specialty, it account for one of the best procedures to treat severe traumas as ballistic wounds. The evolution of forces acting during DO is known to be strongly linked with the clinical issue of the treatment. In this context, the aim of this study was to determine the time-dependent forces supported by a distraction device (DEOS, OBL, France), particularly indicated for severe traumas. Bone transport forces were evaluated for two patients undergoing respectively mandibular and malar DO following a gunshot wound. In order to evaluate the distraction forces, some fixing pins of the distraction device were equipped with strain gauges. Strain values were recorded by means of a data acquisition system (SCXI, National Instruments, USA) connected to a PC computer and executing a LabView program (National Instruments, USA). Records started about one minute before the DO activation and ended about one hour later. Eighteen measurements were done for both cases during the early phases of the treatment. An equilibrium analysis was achieved in order to determine the force and moment acting in bone regenerate from strains in the pins. This procedure was coded through a Fortran program, allowing to plot the evolution of DO force and moment. The present work confirmed the time-dependent feature of the bone regenerate mechanical behaviour. Important data have been obtained concerning forces and their evolution for both mandibular and malar DO.