Twenty six compounds (1-26) were isolated from the root barks of Ulmus davidiana var. japonica. The anti-inflammatory activity of the isolated compounds were evaluated agai nst the generation of inflammatory chemical mediators in bone marrow-derived mast cells. Among them, compounds 10, 11, 13, 15 and 19 inhibited not only cyclooxygenase-2 dependent prostaglandin $D_2$ generation but also 5-lipoxygenase dependent leukotrien $C_4$ generation in a concentration-dependent manner. In addition, compounds 11, 12, 13, 15 and 19 also inhibited $eta$-hexosaminidase release, a marker of mast cell degranulation reaction, from bone marrow-derived mast cell. These results suggest that the anti-inflammatory activity of U. davidiana might in part occur by both the inhibition of eicosanoid generations and the degranulation reaction of mast cells.