The cyclic fatigue resistance of m-pro, M3pro gold, and RaCe glide path files were investigated in a double curved simulated canal. 10 files from each group were examined. The files were tested in s-shaped groove prepared in a block made of stainless steel simulating a double curved root canal. Cyclic fatigue resistance was assessed by counting the number of cycles of separation (NCS). Moreover, the lengths of the separated parts were calculated. All data were analyzed by the one-way analysis of variance. RaCe Scout files showed higher (NCS) significantly compared to m-pro and M3pro gold (P<0.00L) but when compared with each other, no significant difference (P=0.68). According to the results of this study Scout RaCe files had the highest cyclic fatigue resistance in double curved simulated canals among the three types evaluated, therefore, Scout RaCe Files could be used with more trust in preparing of S-shaped canals as the first step of clinical chemo-mechanical preparations.