Objectives:Root canal preparation has been considered the most important phase in endodontic therapy. The objectives of root canal preparation can be defined as cleaning and shaping, including a complete debridment of all areas, leaving the foramen in its original position. To compare the apical transportation in simulated canals with 20o curves, forty five resin blocks were prepared by two rotaries nickel-titanium instruments, Profile.04 (Group P) and K3 (Group K), and a stainless steel hand K-Flexofile (Group C).Methods: By radiografic platform, the double-exposed radiographic technique was used to assess the occurrence and the amount of apical transportation resulting between the initial and the final instrument. The radiographs were scanned and stored in a CD-RW. Utilizing a software Image Tool the radiographic images was ampliated and the distance between the end points of the instruments was measured three times by an examiner who was unaware of the details of the experiment.Results: The mean of the data obtained were analyzed statistically. The results of this study demonstrated that the group C showed greater values of displacements when compared with the others groups, without significant differences among the groups K and P.Conclusions:The rotaries nickel-titanium instruments K3 and Profile.04 enable the root canal preparation with smaller incidence of apical transportantion.