Aim: to evaluate and compare the sealing ability and the adaptability Of two different materials; Mineral Trioxide Aggregate and An innovative Bioceramix when used to seal bifurcation perforation of two different sizes. Methodology: One hundred and twenty multi-rooted human permanent mandibular teeth were used for this study. For sealing assessment twenty specimens were equally divided into negative and positive control groups. Eighty specimens were divided into four equal experimental groups (n=20). For adaptability assessment twenty specimens were divided into four equal experimental groups (n=5). Sealing ability was assessed using dye extraction method while, the adaptability was assessed using scanning electron microscope under (X 500) magnification. Results: results showed that there was no statistically significant difference between the two bioceramic materials MTA and Bioaggregate for sealing and adaptability tests. Conclusion: it was concluded that perforation size had a non-significant effect on sealability of tested materials. Both MTA and Bioaggregate presented acceptable sealability and adaptability with no significant difference between them.