The effect of Sinomenine on IL-8, IL-6, IL-2 and mIL-2R produced by peripheral blood mononuclear cells was investigated by using cell culture, radioimmunoassay and flow cytometry. It was showed that production of IL-8 and mIL-2R was inhibited, but the levels of IL-6 were enhanced by Sinomenine. Our results also demonstrated that Sinomenine did not have any effect on the production of IL-2. The study demonstrated that Sinomenine was able to regulate the production of cytokines. This may be one of the mechanisms by which Sinomenine works on rheumatoid arthritis.