By recently study, GM (Gamipaemo-tang) treatment have worked well on the allergic asthma. The purpose of this study was effect of GM extract on helper T cell, major regulator of immune system. Splenic cells from 8-week BALB/c mice were cultured in GM containing media without activation for 48 hours. The MTS assay and flow cytometry study revealed that lymphocyte treated with GM were not effective on CD4+ T cells. Subsequently CD4+ T cells were isolated and cultured in GM containing media. Either GM were not effective on CD4+ T cell without APCs. By FACS scan analysis, the expression of INF-γ, IL-4 were down-regulated in the condition skewed Th1 and Th2 cells respectively, Using ELISA analysis, the expression of INF-γ is up-regulated and IL-4 is down-regulated in the condition skewed Th1, Th2 cells respectively. With RT-PCR analysis, the expression of mRNA for INF-γ is down-regulated and IL-4 is down-regulated in the condition skewed Th1 and Th2 cells respectively. The result suggests that GM inhibited the differetiation of Th2 cells significantly and indicates GM could enhance anti-allergic immune system.