Background: It has been reported that Mentha arvensis water extract (MAWE) inhibited systemic anaphylaxis and histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80, Objective and method: This study was undertaken to determine the inhibitory effects of immunoglobulin E (IgE)-mediated anaphylactic reaction by MAWE. This paper deals with an evaluation of the effect of 1iIAWE on the anti-dinitrophenyl (DNP) IgE antibody induced anaphylactic reaction in rats. We also investigated the influence of MAWE on anti-DNP IgE antibody-induced tumor necrosis factor-α (TNF-α) production. Results : MAWE inhibited passive cutaneous anaphylaxis (PCA) when intravenously. intraperitoneally, and orally administered. MAWE dose-dependently inhibited histamine release from RPMC activated by anti-DNP IgE antibody. Moreover, MAWE had an inhibitory effect on anti-DNP IgE antibody induced TNF- production from RPMC. Conclusion : These results suggest that MAWE inhibits the IgE-mediated anaphylactic reaction in rats. (J Asthma Allergy Clin Immunol 20: 601-608. 2000)