Aim: To evaluate and compare the sealing ability of a new material, biodentine with MTA when used as a furcation repair material. Material and method: Thirty recently extracted mandibular molars with non-fused well developed roots were collected and intentional furcation perforations were made with a bur. The perforations were repaired with MTA andbiodentine. These specimens were then immersed in 2% methylene blue dye. After their removal, they were sectioned and examined under stereomicroscope to evaluate dye penetration. Results: Demonstrated that furcation perforation repaired with MTA showed decrease in microleakage compared with that of biodentine, However there was no statistical significant difference between the two groups. Conclusion: Both MTA and biodentine showed good sealing ability when used as furcation repair material.