The present study compared the shaping ability and wear resistance of Endo-Eze and ProTaper instruments in curved root canals. Thirty six mesiobuccal root canals of human mandibular molar were randomly divided into the two groups. Crown-down technique was used with applying manufacturer instructions. Each instrument prepared six canals. Pre- and post operative radiographs were taken and then digitally processed. Shaping ability was assessed by measuring the change in canal curvature, preserving dentin thickness by measuring the change in dentin thickness at two fixed levels and wear resistance were examined under stereomicroscope and SEM to evaluation of wear criteria as unused, after 3 used and after 6 used. Both groups recorded lower canal curvature post and pre-instrumentation, however Endo-Eze (AET) system preserved more dentin than ProTaper rotary NiTi system. In Endo-Eze group only one file S3 separation in the 6th canal and showed that increased of defects generally of the all instruments than ProTaper group. It was concluded that reciprocating motion of Endo-Eze stainless steel instruments seem to be effective in maintaining canals curvatures and preserving dentin, but should not be used more than the manufacturer recommendation regarding the numbers of uses. Assessment of cleanliness, surface topography and apical extrusion of debris using Endo-Eze system is required.