The aim of this study was to evaluate the effect of sterilization on the cyclic ‎fatigue resistance of Reciproc Blue rotary files and One Curve rotary files.‎ Methods: ‎For each test of the cyclic fatigue thirty files of each system were used. Ten ‎of the thirty rotary files were used new, ten rotary files after three sterilization cycles and ten rotary files after ‎six sterilization cycles. For cyclic fatigue ‎testing a static model was used ‎with a specific device, which allowed the instruments to ‎rotate freely ‎inside a Stainless-Steel artificial canal. Results: The results showed higher ‎cyclic fatigue of Reciproc Blue than One Curve with no effect of ‎sterilization on Reciproc Blue and decreeing in the cyclic fatigue resistance ‎for One Curve. Conclusions: Reciproc Blue has higher cyclic fatigue ‎resistance than One Curve. With no effect of sterilization on cyclic ‎fatigue of some files while have negative effect on others.