Aim: to evaluate the physical properties, adaptability and biocompatibility of Olive oil / Zinc oxide-eugenol based sealer. Methodology: For physical properties assessment, the methodology used was based upon the ANSI/ADA specification No.57. For adaptability evaluation, twenty extracted lower first permenant single rooted premolars were collected for this study, divided into two equal groups (group I; zinc oxide-eugenol based sealer Z.O.B and gutta percha, group II; olive oil/zinc oxide-eugenol based sealer and gutta percha). Adaptation was evaluated quantitatively and qualitatively. For biocompatibility evaluation, forty five male albino rats were selected for this study, animals were divided into three equal groups where each included 15 rats (group 1; capsules containing Z.O.B Seal sealer. Group 2; capsules containing olive oil. Group 3; capsules containing olive oil/zinc oxide-eugenol based sealer, the capsules were placed subcutaneously at the back of the left legs of the rats. 45 empty capsules were placed subcutaneously at the back of the right legs of the same rats as control. At the end of each evaluation period (two weeks, 1 month and 2 months), 5 rats from each group were anesthetized and sacrificed. Sections were cut, mounted and stained for histopathological evaluation. Results: For physical properties, results showed that there was no statistical significant difference between the two sealers regarding solubility, flow and film thickness tests, while for dimensional stability test, Z.O.B Seal based sealer showed significantly higher dimensional changes than olive oil/Z.O.B Seal based sealer. For adaptability, it was found that group II (Olive/ZOE) presented better adaptation than group I (ZOE) at all levels, with no statistical significance between the two groups at any level. For biocompatibility, olive oil/zinc oxide-eugenol based sealer (group 3) showed to be well tolerated by the subcutaneous tissue of the rat in all periods of evaluation. Conclusions: Olive oil proved to enhance the dimensional stability and adaptability of zinc oxide-eugenol based sealers. Olive oil/Z.O.B Seal based sealer can be considered a biocompatible sealer to be used.