Ellagic acid is known to have anti-oxidant, anti-carcinogenic and anti-mutagenic effects. However, roles of ellagic acid in the immediate-type allergic reactions have not yet been investigated. In the present study, we have demonstrated that ellagic acid attenuates immunoglobulin (Ig)E-mediated allergic response in mast cells and in vivo. Oral administration of ellagic acid inhibited anti-dinitrophenyl (DNP) IgE-mediated passive cutaneous anaphylaxis. Ellagic acid dose-dependently reduced histamine release and the expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-6 in rat peritoneal mast cells (RPMC) activated by anti-DNP IgE. Moreover, ellagic acid suppressed an increase in intracellular calcium ion concentration ([Ca(2+)](i)) in RPMC. Furthermore, ellagic acid decreased the activation of nuclear factor-kappa B (NF-kappaB). Decreased NF-kappaB activity as well as reduced [Ca(2+)](i) might be involved in the inhibitory effect of ellagic acid on the secretory response. Our findings provide possibility that ellagic acid may serve as an effective therapeutic agent for allergic diseases.