This paper aims to evaluate the stress characteristics within the dental implant influenced by different implant wall thicknesses as a result of varying diameters of 3.5 and 5.5mm. A two-dimensional finite element model of the implant and mandibular bone consisting of triangular and quadrilateral plane strain elements is analysed to compute the von Mises stresses in the implant subjected to varied masticatory forces and abutment screw preloads. As expected the implant wall thickness significantly influences the stress magnitude and distribution pattern within the implant. Stress concentrations generally occur at the top of the implant as well as around the notch. When the wall thickness is reduced, stress concentrations are also found around the first external implant thread. The results also show that the masticatory force is more influential on the stress within the implant than the abutment screw preload.