The initiation of immunoglobulin E (IgE)-mediated allergic reactions requires binding of IgE antibody to its high-affinity receptor. Human basophilic KU812F cells express $Fc{varepsilon}RI$ on the cell surface and act as effector cells in the allergic response. In this study, we investigated the effects of Scutellaria radix extract on the expression of the $Fc{varepsilon}RI$ in human KU812F cells. Flow cytometric analysis showed that S. radix extract treatment caused a concentration-dependent decrease in $Fc{varepsilon}RI$ expression on the cell surface. Furthermore, the level of $Fc{varepsilon}RI$ ${alpha}$, ${eta}$, and ${gamma}$ chain mRNA in KU812F cells was examined by RT-PCR. S. radix extract reduced total cellular $Fc{varepsilon}RI$ $alpha$ and ${gamma}$ chain mRNA expression in a concentration-dependent manner. $Fc{varepsilon}RI$-mediated histamine release was reduced from $21.75{pm}1.34;ng/10^6$ cells in non-treated cells to $16.46{pm}1.98;ng/10^6$ cells in S. radix extract treated cells. These results suggested that S. radix extract has the potential to down-regulate of FcRI expression and to inactivate basophils.