Gamimahaenggamsuk-tang (GMHGST) is used for treatment of inflammatory diseases including rheumatoid arthritis (RA). Here, regulatory activity of GMHGST on RA-mediated inflammatory responses was investigated in cultured human fiDroblast-like synoviocytes (FLS), Levels of mRNAs encoding for inflammatory cytokines such as $IL-1{eta}$, IL-6 and IL-8 and NOS-II enzyme, which had been induced by $TNF-{alpha}$ and $IL-1{eta}$ cotreatment, were decreased to the similar levels as those in cells treated with anti-inflammatory agent MTX. mRNA expressions of matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinases (TIMPs) as well as intercellular adhesion molecule (ICAM) were also downregulated by increasing doses of GMHGST in activated FLS. Moreover, GMHGST appeared to protect cells by decreasing NO levels, and inhibited cell proliferation which had been induced by inflammatory stimulation by $TNF-{alpha}$ and IL-1. These results suggest that GMHGST is effective as an inhibitory agent for regulating inflammatory responses in activated FLS.