Aim: The aim of this study is to evaluate R-Endo R3 file's resistance to cyclic fatigue in comparison with continuous rotation movement and 'Adaptive Motion' (AM) movement under dynamic model. Materials and Methods: Forty pieces of R-Endo R3 (25.04) files (lot no: 062011) were included in the study. Cyclic fatigue tests were performed with specifically manufactured dynamic cyclic testing device. The device has an artificially prepared canal with 60° curvature angle and 5 mm curvature radius. The canal inner diameter is 1.5 mm and the center of curvature is located 5 mm coronally from the apex. The files were randomly divided into two groups (n = 20) and the following procedures were performed - Group 1: Rotary motion (RM), Group 2: AM. Time to fracture was recorded and the number of cycles to failure for each instrument was obtained. Statistical analyses were performed using Student's t-test. The statistical significant level was set at P < 0.05. Results: AM group had a significantly higher cyclic fatigue resistance compared with RM group (P < 0.001). Conclusion: Within the limitation of the present study, it was found that 'Adaptive Motion' statistically increases the resistance to cyclic fatigue of R-Endo R3 files, manufactured for retreatment.