Objectives: Gagamyanggyeoksan (G-YGS) has been used to suppress allergic reaction, however, the cellular target of G-YGS and its mode of action remain unclear. The present study was designed to investigate the effect of extracted G-YGS on the PMA and lonomycin (PI)-induced activation of RBL-2H3. Methods: For this investigation, We examined IL-4, IL-13 mRNA expression by Real-Time PCR, IL-4, IL-13 production by ELISA analysis and manifestations of GATA-1, GATA-2, NF-AT1, NF-AT2, AP-1 and NF-${kappa}B$ p65 transcription factors by western blotting, OVA-specific IgE, IL-4, IL-13 by mouse be sensitive to OVA. Results: Here we showed that treatment of RBL-2H3 mast cells with G-YGS, suppressed PI-induced production of Th2 cytokines including IL-4 and IL-13 in a dose dependent manner. The mRNA expression of IL-4 were completely abolished by G-YGS at the concentration of $100{mu}g/ml$. Data from a stable cell lines consistently expressing IL-4. And the mRNA expression of IL-13 were abolished by G-YGS at the $200{mu}g/ml$. But there is no difference between the $50{mu}g/ml$, the $100{mu}g/ml$ and the comparison. Results from the western blot analysis of transcription factors involving IL-4 and IL-13 expression indicated that it prominently decreased the expression of mast cell specific transcricption factors including GATA-1, GATA-2, NF-AT2, c-Jun, NF-${kappa}B$ p65 but not c-Fos. And G-YGS suppressed IgE, IL-4, IL-13 in mouse be sensitive to OVA. Conclusions We suggested the anti-allergic activities of G-YGS might be mediated by down-regulation of Th2 cytokines such as IL-4 and IL-13 through the regulation of transcription factors as GATA-1, GATA-2, NF-AT2, c-Jun, NF-${kappa}B$ p65.