Mast cells and basophils are important effector cells in immunoglobulin-E (IgE)-mediated allergic reactions. Using the human basophilic KU812F cells, we assessed the inhibitory effects of 6-methoxyluteolin, isolated from Chrysanthemum zawadskii, in the $Fc{varepsilon}RI$-mediated allergic reaction. We determined that 6-methoxyluteolin inhibited anti-$Fc{varepsilon}RI$ ${alpha}$ chain antibody (CRA-1)-induced histamine release, as well as elevation of intracellular calcium concentration $[Ca^{2+}]_i$ in a dose-dependent manner. Moreover, the inhibitory effects of 6-methoxyluteolin on the cell surface expression and the mRNA level of the $Fc{varepsilon}RI$ ${alpha}$ chain were determined by flow cytometric analysis and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Therefore, these results show that 6-methoxyluteolin is a potent inhibitor of histamine release and calcium influx via down-regulation of the $Fc{varepsilon}RI$ ${alpha}$ chain.