Objectives: To evaluate the apical microleakage of two coated carrier systems in comparison wíth cold lateral compaction technique(LC). Methods: 40 extracted single-rooted teeth were assigned into two groups: Group 1: roots were instrumented with System GT rotary files (Dentsply, Switzerland). Of these, 10 randomly selected teeth were obturated with a coated carrier filling system (GT Obturator, Dentsply, Switzerland) and the remaining 10 with LC. Group 2: Teeth were instrumented Profile Ni-Ti rotary files (Dentsply, Switzerland). 10 teeth were randomly obturated with Thermafil system (Dentsply,Switzerland) and the remaining 10 with LC. Topseal sealer (Dentsply, Switzerland) was used in all groups. Filled roots were stored at 370C at 100% humidity for 48h.Consequently coated with two layers of nail varnish, leaving the apical foramen exposed. Specimens were immersed in 2% methylene blue dye for 48h, rinsed in tap water and removed off the varnish by gentle scraping. The specimens were demineralized in 5% nitric acid solution for 72h, dehydrated in ascending grades of alcohol, immersed in methyl salicylate and cleared. Digital images of specimens were obtained and transferred to a PC. Apical leakage was measured (in mm) as the distance from anatomic apex to the maximum extent of coronal dye penetration. Non-parametric data were subjected to Mann-Whitney U test (p=0.05) for intragroup statistical comparisons. Results: Maximum dye penetration scores for GT Obturator and LC were 4 and 3,5 mm, respectively. There was no significant difference between apical microleakage scores of GT Obturator and LC (p>0.05). Similar findings were obtained in Group 2 (p>0.05), with Thermafil showing less microleakage than its controls. Maximum dye penetration scores for Thermafil and LC were 0.5 and 4 mm, respectively. Conclusion: Root canals instrumented with the tested rotary files may exhibit less microleakage when obturated consequently with their relevant core filling systems, compared to LC.