This study was carried out to know the immunity responses of the Spatholubus suberectus Dunn(hereinafter referred to STSD) to the synovial cells isolated from patients with rheumatoid arthritis. Various experiments were performed in vitro to analyse the immunity effects of STSD. Gene expression and production of pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, iNOS and COX-2 were determined by RT-PCR and ELISA kit. And also the binding activity of NF-kB and AP-1 were measured by Electromobility shift assay (EMSA) and the production of ROS was measured by flow cytometry. The results were obtained as follows 1. The gene expression and production of pro-inflammatory cytokines IL-1β, IL-6, TNF-α were reduced significantly. 2. The gene expression of iNOS and COX-2 were reduced. 3. The binding activity of NF-kB and AP-1 were inhibited. 4. The production of ROS in human synovial cells was reduced significantly. Comparison of the results for this study showed that STSD had immunomodulatory effects of suppressing or enhancing. So we expect that STSD should be used as a effective drugs for not only rheumatoid arthritis but also another auto-immune disease. Therefore we have to survey continuously in looking for the effective substance and mechanism in the future.