Objective: To evaluate the apical sealing ability of 2 epoxy resin-based root canal sealers used with 2 different warm gutta-percha obturation techniques and cold lateral condensation. Method and Materials: The root canals of 72 freshly extracted single-root incisors were prepared and randomly assigned to 6 experimental groups. Root canal fillings were performed using either cold lateral condensation, warm vertical condensation, or Thermafil obturators with EndoRez or AH Plus as sealer. After root canal filling, the teeth were stored in 5% methylene blue solution for 7 days. Linear dye penetration was measured in bisected specimens by a calibrated investigator using a light microscope. Results: Statistical analysis revealed significantly higher penetration depths in groups where EndoRez was used (P .05, Tukey test). Regarding the different obturation techniques, the least amount of dye penetration was observed for AH Plus and EndoRez when warm vertical condensation was used. Conclusion: The results of this study indicate that the apical sealing ability of EndoRez is not as effective as that of AH Plus. Thermafil obturators and warm vertical condensation achieved seals with low dye penetration depth. The use of these techniques might decrease the risk of apical leakage. Keywords: apical seal, cold lateral condensation, dye penetration, obturation techniques, resin-based sealer, Thermafil obturation, vertical condensation