purpose: to evaluate canal transportation of three different rotary nickel titanium (Ni-Ti) preparation systems including Spring Endo, Spring H and ProTaper Next files using cone beam computed tomography (CBCT). Materials and Methods: 30 extracted human mandibular first molars with similar range of mesiobuccal canal curvature (20-40o) were used. samples were randomly divided into three groups (n=10) according to the type of used instruments. Group 1: Spring Endo, Group 2: Spring H and Group 3: ProTaper Next. Pre-and post-instrumentation CBCT images were recorded at 3,5, 8 mm levels from the apex under the same circumstances, then canal transportation was calculated using specific equation. Results: concerning root canal transportation, Group1 (Spring Endo system) showed the highest mean canal transportation value while the lowest value was recorded for Group 2 (Spring H system). One-Way ANOVA revealed a statistical significant difference among the tested groups at the three levels. Tukey's pair-wise comparison test revealed statistical significant differences between groups 1 and 2 at all canal levels , while statistical significant differences between group 1 and 3 were found at all canal levels in mesio-distal direction and only at 5 mm in bucco-lingual direction. Comparison of canal transportation at the selected three root canal levels regardless of the used preparation systems revealed that the least canal transportation was recorded at 8mm level and the highest root canal transportation at 3mm level. Conclusion: root canal transportation reduction depends on the type of used file system alloy and its modification rather than its spring machining.