Human basophilic KU812F cells express a high affinity for IgE receptor, $Fc{varepsilon}RI$, which plays an important role in immunoglobulin E (IgE)-mediated allergic reactions. Using the human basophilic KU812F cells, we assessed the inhibitory effects of the ethanolic extract from Chrysanthemum zawadsaki(CZ) on $Fc{varepsilon}RI$ ${alpha}$ chain expression. Flow cytometric analysis showed that cell surface $Fc{varepsilon}RI$ ${alpha}$ chain expression was suppressed when the cells were cultured with CZ extract. RT-PCR analysis showed that the mRNAs for $Fc{varepsilon}RI$ ${alpha}$ chain decreased by the treatment of CZ extract. Moreover, CZ extract was also observed to result in a reduction in the release of histamine from anti-$Fc{varepsilon}RI$ antibody (CRA-1)-stimulated cells. These results suggest that CZ extract may exert anti-allergic activity through down-regulation of $Fc{varepsilon}RI$ ${alpha}$ chain expression and a subsequent decrease in histamine release.