Aim: to compare the shaping ability of NiTi hand instruments with Stainless- steel instruments in preparation of curved root canal in extracted teeth. Materials and Methods: a total of 24 of curved root canal were randomly divided into two groups. One group was prepared using stainless steel instruments and the other prepared NiTi instruments. Curvatures pre-and post instrumentation were registered and compared. And straightening of the canals were determined by autocad analysis system. Results: two systems were significantly changed the original canal curvature with no differences between both systems. However, the time required to finish preparation was significantly less with NiTi system. Conclusion: under the conditions of this study, it can be concluded that two hand instrumentation system changed the original canal curvature, but the time consuming to finish the preparation was less with NiTi hand system.