Aim: Aim of the study is to evaluate the lateral forces on the instrument in the apical 3rd of curved canal with two Nickel Titanium rotary systems. Methodology: One brand of instrument ProTaper F2 was scanned with micro computed tomography to produce a real-size, 3-dimensional (3-D) model and was compared with Anexas (designed by author). The stresses on the instrument during simulated shaping of the root canals were analyzed numerically by using a 3 D finite element package, taking into account the nonlinear mechanical behavior of the NiTi material. Results: Anexas shows lowest values for force generation in the apical 3rd of canal as compared to Protaper which shows higher values. Conclusion: With FE simulation of root canal shaping by 2 files, it was observed that different instrument designs would experience unequal degree of force generation in canal, as well as reaction torque from the root canal wall.