INTRODUCTION: Mechanical overload is thought to be one of the major causes of implant complications. It may induce loosening and fracture of the superstructure and/or implant components. Bone loss may also occur at the implant-bone interface. Increasing the diameter and length of the implant decreased the stress and strain on the alveolar crest, but diameter had a more significant effect than length to relieve the crestal stress and strain concentration. When the mesiodistal dimension is greater than 14 mm, using at least two implants to restore the region should be considered. When two implants replace the molar region, the mesiodistal offset loads to the prosthesis can be eliminated. OBJECTIVES: Evaluation of the axial and off axial loading on implants of different diameters for replacing first mandibular molar. MATERIALS AND METHODS: Fifteen epoxy resin blocks in which implants of different diameters were fixed. Specimens were divided into 3 parallel groups, 5 specimens each according to the implant diameter. Evaluation of the strain distribution around the implants under vertical axial and off axial loading using the strain gauge was done. RESULTS: The total microstrain mean value of the double implants was significantly less than the 6mm wide implant and the 4.7mm diameter implant. CONCLUSIONS: On using dental implants for replacing mandibular first molar, double (3.75-3.75) mm diameter implants revealed reducing microstrains than 6-mm-diameter implant and 4.7 diameter implant and give wider support to the crown restoration leading to elimination of the mesiodistal cantilever.