Objectives: Preload on abutment screws may induce clamping force between the implant and abutment, which may cause the implant deformation and induce peri-implant bone strain. This study's aims were to evaluate whether antirotational design at implant-abutment interface and the application of a counter torque device during preload will affect the development of peri-implant bone strain after preload of the abutment screw. Methods: A stacked delta rosette strain gauge was bonded on 5 mm diameter Nobel Biocare implant replica. The strain gauge was bonded 1.5 mm away from the abutment-implant junction with one gauge paralleled the axis of the replica. Then the replica assembly was embedded in an epoxy resin block, 12x22x70 mm. A 3mm-height Nobel Biocare MirusCone abutment (MC) with antirotational implant-abutment design and its configuration counterpart, without antirotational design, MultiUnit abutment (MU) were used for testing. The abutment screw of each abutment was tightened, with or without the counter-torque device (wct and woct, respectively) to 20 N-cm with an electronic torque controller. Three models were fabricated and each group (MC+wct, MC+woct, MU+wct, MU+woct) was tested 5 times. Values from the three gauges of the rosette were transformed into the value and direction of maximum principle strain (MPS) according to a formula provided by the manufacture. Results: The data showed that preload of the abutment screw may induce peri-implant bone strain with direction closed to the long axis of the implant replica and the MPS was not statistically significantly between MC+wct(-228.0°"33.7£g£`), MC+woct(-210.5°"46.2£g£`), MU+wct(-222.0°"21.4£g£`), and MU+woct(-207.9°"18.9£g£`) groups. Conclusion: The data suggest that peri-implant bone strain may be developed after preload and the existence of implant-abutment anti-rotational design or not did not significantly affect the values. Supported by NTUH93N005.