Objective: To assess the long-term sealing ability of a new dual-curable, self-etching, 4-META containing resin-based sealer: Hybrid Root SEAL (MetaSEAL in the United States) and compare with RealSeal and AH Plus sealers. Methodology: Root canals of 44 extracted and decoronated single-rooted human teeth were instrumented using a crown-down technique with ProFile 0.04 tapered NiTi rotary instruments to ISO size 30 and then to size 45 with K-hand files. Four roots were selected and used as positive and negative controls (n = 2), the rest were randomly divided into 4 groups (n = 10) and filled using 0.04 tapered size 45 cones as follows: Group 1: AH Plus with gutta-percha; Group 2: Hybrid Root SEAL (MetaSEAL) with gutta-percha; Group 3: Hybrid Root SEAL (MetaSEAL) with Resilon point; and Group 4: RealSeal with Resilon point. The quality of seal of each specimen was measured after 1, 4, 12, and 24 weeks using a fluid transport model. Measurements were made at 2-minute intervals for 8 minutes. The data were calculated as Lp and statistically analyzed using 2-way repeated measures of ANOVA and Bonferroni pairwise comparison tests (α = 0.05). Results: There were no significant differences among test materials in terms of fluid microleakage values (P = .126). There were statistically significant differences among the time periods (P = .009) and observed between 1- and 24-week test periods. There was significant interaction between root canal filling materials and time of testing (P = .048). Conclusion: Within the limitations of this in vitro study, it was concluded that recently introduced Hybrid Root SEAL (MetaSEAL) showed similar sealing performance with RealSeal and AH Plus sealers when used either with gutta-percha or Resilon at 24 weeks. © 2008.