Despite advantages of NiTi instruments, fracture is the most common procedural error that occurs during clinical use. But various studies reveals that before undergoing fracture these NiTi files may also undergo some distortions after use in certain number of canals. These distortions can be in the form of unwinding of flutes, microcracks, pitting or surface wear. So, it is important to check the instruments for signs of wear and deformation every time it is used in order to avoid the complication of instrument separation. The aim of this study was to comparatively evaluate the distortion of three files - Hand Protaper, Rotary Profile and new Twisted Ni-Ti file using scanning electron microscope after invitro use.Within the experimental protocol of this study,it was found that Ni-Ti endodontic files should be used carefully and in the prescribed manner only and should be checked visually under magnification after every use and those found distorted should be discarded immediately.The new manufacturing processes of NiTi endodontic files also appeared to offer greater resistance to fracture over the traditional process.