Objective: The objective of this study was to compare the shaping ability of different rotary instruments operated either with continuous rotation or with reciprocating motion using Reciproc and WaveOne systems compared with ProTaper system in curved canals of simulated resin blocks. Methods: A thirty resin blocks with simulated curved canals (VDW, Munich Germany) were divided into three groups, ten blocks in each group. Teeth were prepared according to manufacturers' recommendation for each corresponding system. Preoperative and postoperative photographs were taken using digital camera (450D Canon) with micro lens (Canon EF 100mm. F/2.80). A fixed positioner was maintained for standardization and reproducibility. Measurements were made on superimposed pre and post instrumentation digital images and were carried out with Adobe Photoshop (CS3 Extended, version 10) at four points: orifice (O), beginning of the curve (BC), apex of the curve (AC) and end-point (EP). Difference in shaping ability and the amount of canal transportation were analyzed using one-way ANOVA test. Difference giving a p-value of <0.05 were considered statistically significant. Results: All instruments maintained the original canal curvature with significant difference between different files. The Pro-Taper group caused significantly greater widening of canals than Reciproc system at all points except at orifice level (P<0.05). Reciproc system showed the least amount of resin removed at all points. Pro-Taper system showed the highest transportation at all points except EC point (p<0.05). Reciproc showed the least transportation at all points. The direction of transportation at all points was toward the outer curvature except in Reciproc at BC and EP points. The Pro-Taper and WaveOne showed minor transportation toward the outer curvature, both groups caused significantly greater transportation than Reciproc at the BC point. Conclusion: Under the conditions of this study, all instruments maintained the original canal curvature and were safe to use. Reciproc system showed a better shaping ability than other systems at all points. ProTaper had the highest tendency for transportation.