Objective: The purpose of this study was to compare the effect of eugenol-based and resin-based endodontic sealers on the push-out bond strengths of prefabricated fiber posts luted with different resin cements. Method and Materials: Ninety prefabricated fiber posts were luted into extracted singlerooted teeth with one of three resin cements (Variolink II, ParaCore, or Rely X Unicem). Each group was subdivided into three groups with 10 teeth each. The first two groups were obturated with gutta percha and one of two eugenol-based endodontic sealers (Endofil or TubliSeal) each. The third group was obturated with gutta percha and (AH26) resin-based root canal sealer. Push-out tests were performed in a universal testing machine by applying a load speed at 0.5 mm/min by using a 1-mm-diameter metallic plunger which induced a load in an apical to coronal direction. The maximum value for post dislodgement (in Newtons) was recorded. Data were collected and statistically analyzed using two-way ANOVA and Tukey multiple comparison tests (α = .05). Results: The highest mean bond strength values were recorded for the AH26 sealer group (non-eugenol sealer) luted with Rely X Unicem resin cement (mean ± SD = 326.1 ± 66.1 N), while the lowest mean bond strength values were observed with posts luted with Variolink II resin cement into canals obturated with gutta-percha and Endofil (eugenol-based) sealer (90.3 ± 25.2 N). There was no significant difference between the means of push-out strengths for the Endofil and TubliSeal groups (P = .745). Conclusion: Eugenol-based sealers (Endofil and TubliSeal) significantly reduced the push-out bond strength of prefabricated fiber posts luted with resin cement. Keywords: bond strength, endodontic sealer, eugenol, fiber posts