Aim of the study: The objective was to asses and compares the effect of PEEK and Zirconia primary copings in milled double crown PEEK framework. Materials and methods: One cast was fabricated simulating Kennedy Class I with the premolars as the last standing abutment. The primary copings were classified into two groups, milled PEEK group I and milled Zirconia group II. Two milled PEEK frameworks were used. Four strain gauges were installed bilaterally in the model. A load of 100 N was applied to the area of the first molar bilaterally. The same procedure was repeated 10 times. Cyclic loading was applied simulating 1 year of function. Strains induced on the abutments during bilateral loading were evaluated before and after chewing simulation. Results: The highest compressive micro-strain was recorded at channel (4) after cyclic loading for PEEK group 359.00±5.055 µm/m followed by channel (2) 356±13.293 µm/m. While the least compressive micro-strain was recorded at channel (1) before cyclic loading for the Zirconia was 150±7.817 µm/m. There was significant difference in channels (2) and (4) regarding PEEK group before and after cyclic loading. While for Zirconia group there was significance difference in channels (1) and (3) before and after cyclic loading where P value was