In order to promote the osteosynthesis of a fractured bone, the complete immobilization of the fracture is needed. The surgical plates used have to respond accordingly to forces and deformations which can appear during daily activities or during stress conditions. Nowadays, finite element models are used to design implants, analyze the influence of different factors such as, size, shape, position, elastic modulus, etc. or to study bone variables, such as, geometry, bone density and anisotropy distributions and response to different load conditions. Following this trend, the paper presents a numerical analysis, using Finite Elements Method, of LN 331 S plate stress and deformation when reduces a parietal bone fracture.