1. Objective : The purpose of this study is to investigate the effects of TAM (Taraxacum mongolicum) on Th2 cytokine production in MC/9 mast cells. 2. Methods : The effects of TAM was analyzed by ELISA and Real-time PCR in MC/9 mast cells. Levels of IL-5, IL-13 were measured using enzyme-linked immunosorbent assays(ELISA). mRNA levels of IL-4, IL-5, IL-6, IL-13 were analyzed with Real-time PCR. 3. Results : 1) TAM inhibited the IL-4 production significantly in comparison to PI-control group at concentration of $50{mu}g/ml$, $100{mu}g/ml$, $200{mu}g/ml$. 2) TAM inhibited the IL-13 production significantly in comparison to PI-control group at concentration of $50{mu}g/ml$, $100{mu}g/ml$, $200{mu}g/ml$. 3) TAM inhibited the IL-4 mRNA expression significantly in comparison to PI-control group at concentration of $100{mu}g/ml$. 4) TAM inhibited the IL-5 mRNA expression significantly in comparison to PI-control group at concentration of $50{mu}g/ml$, $100{mu}g/ml$. 5) TAM inhibited the IL-6 mRNA expression significantly in comparison to PI-control group at concentration of $100{mu}g/ml$. 6) TAM inhibited the IL-13 mRNA expression significantly in comparison to PI-control group at concentration of $100{mu}g/ml$. 4. Conclusions : These results indicate that TAM (Taraxacum mongolicum) has the effect of decreasing the Th2 cytokine production in the MC/9 mast cell.