Autoimmune inflammatory diseases, such as rheumatoid arthritis (RA), have been thought to be mediated by the cytokine interleukin 17 (IL-17). Curcumin (1,7-Bis (4-hydroxy-3-methoxyphenyl)-1,6 heptadiene- 3, 5-di-one) is an active ingredient derived from rhizomes of Curcuma longa Linn., displaying remarkable anti-inflammatory. Curcumin has been re-ported to have the suppressive effect on the development of an experimental animal model of RA, collagen-induced arthritis (CIA). However, there is no evidence for the effect of cur-cumin on IL-17 production of CIA mice. In the present study, we demonstrated that curcu-min inhibited the production of IL-17 in vitro. The treatments of curcumin exhibited an in-hibitory activity against CIA. We further demonstrated that curcumin suppressed IL-17 production of CIA mice using enzyme-linked immunospot assay and intracellular cytokine staining. We reported that curcumin had the inhibitory activity on IL-17 production in CIA mice. The suppression of CIA might result from the inhibition of IL-17 production.