This work was performed to investigate the protective effect of ethanol extract (AEx) from acorn (Quercus acutissima CARR.) against allergic mediated responses in asthma model cells and mice. The AEx inhibited antigen-stimulated cytokine production such as interleukin (IL)-4, IL-13 and tumor necrosis factor-${alpha}$ (TNF-${alpha}$) and AEx also inhibited intracellular reactive oxygen species (ROS) generation against IgE-mediated allergic response in rat basophilic leukaemia RBL-2H3 cells. The ovalbumin (OVA)-sensitized mice were orally administered with AEx (100 or 300 mg/kg) and authentic tannic acid (75 mg/kg) every day for 15 days. Increased TNF-${alpha}$ production by OVA-sensitization/challenge was significantly reduced by administration of AEx. The serum triglyceride levels of asthma mice were significantly reduced after feeding for 15 days with tannic acid or AEx. The mice fed with tannic acid or AEx also exhibited a significant reduction in body weights compared to those of asthma control group. The AEx increased the heme oxygenase (HO)-1 mRNA expression in the asthma model mice and showed DPPH radical scavenging activity. These results indicate that AEx protects against IgEmediated allergic and OVA-induced asthmatic responses via direct and indirect antioxidant activities. Reduced triglyceride and body weights may provide additional protective benefits of AEx on allergic asthma.