The effect of aqueous extract of Mentha arvensis L. var. piperascens Malinv. (Labiatae) (MAAE) on immunologic and nonimmunologic stimulation-mediated anaphylactic reactions was studied. Nonimmunologic anaphylactic reaction was induced by compound 48/80 injection. MAAE (0.005 to 0.5 g/kg) inhibited systemic anaphylactic reaction induced by compound 48/80. Immunologic anaphylactic reaction was generated by sensitizing the skin with anti-dinitrophenyl (DNP) IgE followed 48 h later with an injection of antigen. MAAE (0.001 to 1 g/kg) dose-dependently inhibited passive cutaneous anaphylaxis (PCA) when intraperitoneally, intraveneously and orally administered. MAAE (0.001 to 1 mg/ml) dose-dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. Moreover, MAAE (0.1 mg/ml) had a significant inhibitory effect on anti-DNP IgE-mediated tumor necrosis factor-alpha (TNF-alpha) production. These results indicate that MAAE inhibits immunologic and nonimmunologic stimulation-mediated anaphylactic reactions and TNF-alpha production from RPMC.