Objective: The aim of this study was to compare the sealing ability of MineralTrioxide Aggregate (MTA) and Biodentine when used to repair the furcal perforations in permanent molars using dye extraction method. Study design: Recently extracted permanent molars were collected and randomly sealed with MTA and biodentine, after preparing perforations in the furcation area by using a high- speed long shank round bur No:4. After setting of the material, specimens were kept in methylene blue dye for 24 hours to check the microleakage by the dye extraction method. Samples were then placed in vials containing 1ml of 65% nitric acid for three days for the extraction of the dye. The vials were centrifuged at 14000 rpm for 5 minutes to separate debris from the extracted dye. About 200 microlitres of the supernatant from each sample was then analyzed in a UV-visible spectrophotometer at 550nm wavelength using concentrated nitric acid as the blank, and readings were recorded as absorbance units.