Investigation of the stress distribution during mandible fracture fixation with plates has been performed in this study. This subject continuous the previously started complex research based on an investigation of a particular mandible. Attempts performed so far at such finite element models have been limited by the coarseness of the mesh and the degree of material property inhomogeneity utilized. The purpose of the present study was to simulate the placement of the fixation plate and screw location. The previously developed three-dimensional finite element model of the mandible consisted of a hard shell with a cancellous bone compound inside. Both, an orthotropic material model and trabecular bone inhomogeneity were used for the simulation of the mandible. A nonsymmetric geometry of axis-symmetric loading was adopted for the muscle forces simulation on the plate fixed fractured mandible. The present study is supposed to reveal the recommendations for surgical manipulations. This could help to optimise the effective procedure of plate fixation by screws to the mandible and maxilla. The finite element method developed is especially well suited to analyse the bonded interface bone-fixation device, as it is capable of accurate calculation the stress field at this location. The prediction of the mechanical interaction between a fixation plate and the fractured mandible fragments can provide useful information for the surgeon with respect to the used plate system (rigid or soft) and surgical technique.