Objectives : Ulmus davidiana (UD) has been widely used in Korean herbal medicines used for treatment of acute and chronic inflammatory diseases, such as rhinitis, asthma, and abscess. In this study, To investigated the protective effect of UD on type 1 allergic response, we determined whether UD inhibits early and late allergic response. Methods : The effect of UD was analyzed by ELISA and RT-PCR in RBL-2H3 cells. Levels of ${eta}$ -hexosaminidase, interleukin (IL)-4 and TNF-${alpha}$ were measured using enzyme-linked immunosorbent assays (ELISAs). mRNA levels of COX-2 and T-helper type 2(Th2) cytokines were analyzed with RT-PCR. Results : We found that UD suppressed ${eta}$-hexosaminidase release in RBL-2H3 not only by the PMA plus A23187 stimulation, but also by the IgE-DNP-HSA stimulation at the antigen-antibody binding stage and antibody-receptor binding stage. UD also significantly inhibited COX2 level, along with reduced Th2 cytokine levels, such as IL-3, IL-4, IL-5, IL-13, GM-CSF, and TNF-${alpha}$ in RBL-2H3. Conclusions : Our results indicate that UD protects against type 1 allergic response and exerts an anti-inflammatory effect through the inhibition of degranulation and expression of COX2 and Th2 cytokines.