Tunisian olive oils have been traditionally used as a medicinal food for chronic inflammation. To investigate the antiallergic effect of virgin olive oil samples from five principal olive varieties grown in various regions of Tunisia, we used the type I allergy reaction model using rat basophilic leukemia (RBL-2H3) cells and different dilutions of olive oil samples to determine beta-hexosaminidase release inhibition at two different response stages. Results showed that the Sayali olive oil significantly inhibited beta-hexosaminidase release by the IgE antibody-sensitized, BSA antigen-stimulated RBL-2H3 cells at the antibody-antigen binding stage. The result of our experiment shows that the anti-allergic effect of olive oil at this binding stage may be dependent on their flavone content. The Zarrazi olive oil significantly inhibited beta-hexosaminidase release at the antigen-receptor binding stage. Moreover, we investigated the effect of olive oil samples on histamine release and production of cytokines by activated human basophilic (KU812) cells. Different dilutions of Sayali olive oil dose-dependently inhibited the production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4), and different dilutions of Zarrazi olive oil dose-dependently inhibited histamine release and IL-4 production by calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA)-stimulated KU812 cells.