Introduction: A broken instrument within the root canal is a panic problem which one should never wish to occur during routine endodontic therapy. However, the decision regarding how to manage this problem is complex. Therefore, the clinician must evaluate carefully the options of treatment; retrieving the instrument; bypassing the instrument; or leaving the fractured instrument in the canal as part of the final root canal filling. Objective: The objective of this study is to compare the sealing ability of three obturation techniques over apically broken nickel-titanium (Ni-Ti) ProTaper file. Materials and methods: Forty eight extracted human single-rooted mandibular premolars were prepared using ProTaper files (PT) and subjected to breakage of 3mm from F5 tip at the apical one third of the canal. The canals were randomly divided into three groups of 12 teeth each according to type of obturation technique; E&Q plus obturation, using a Thermafil obturator, or lateral compaction technique. The remaining 12 teeth served as positive controls which contained canals with apically broken files only without any type of obturation. Apical leakage was assessed by the dye penetration method in which all teeth were immersed in 2% methylene blue dye for 48 hours. Then the specimens were longitudinally split into two halves. Linear dye penetration was measured in millimeters under a stereomicroscope for each specimen. Statistical analysis of the results was performed using Kruskal-Wallis and post hoc tests. Results: The results showed no statistically significant difference in apical leakage between the three obturation techniques used over apically broken F5 files. Conclusions: All obturation techniques used over apically broken PT files played a significant role in the sealing ability